Ive just travelled the world for a year.
1. 5DMKIII was awesome, 5DS is great but possibly overkill if you already have the III. You do have to be so careful with them in comparison especially for documentation work and fast paced environments and its worth roughly twice the amount. 5DMKIII will do the trick unless your desperate for a new body.
2. I took 5DMKIII 7DMKII 24-105mm 100-400mm MKII 16-35mm F2.8 MKII 11" MBA 2x4tb hdds and a 1tb SSD which were split in different bags this with a couple of extras weight about 12-15kg as my day pack... then I had a 25-30kg pack for my essentials. It was too heavy on many occasions and I wish I had packed lighter but in the end I used all the equipment in the different continents I was in. My main objective was wildlife, landscape and documentary work. My GF also had a 70D 18-135 a 55-250mm and a go pro hero 4 Black so we had a lot of gear with us.
Analyse your gear and ensure you need every component. My first trip I took a 5DMKIII 24-105 16-35 and 70-300mm L half the weight, half the gear and perfect for 90% except wildlife was really disappointed while in the amazon so decided to go bigger this time and with a crop camera which worked wonders!!! 7DMKII was a brilliant camera for the wildlife aspect.
First trip I took a 128gb iPad Mini 2 and a UDMA colorspace image loader which worked brilliantly, had an extra 2tb which i moved the raws from the UDMA when I had a computer to use double backup. Shot jpg to the SD and raw to the CF and transferred the jpg to the iPad and raw to the UDMA and used PS express to edit them o the iPad and it was great! But i had some issue with the colour of the iPad, edits looked great on screen but when posting on here they looked way more saturated to the forum which I was told about big time lol! Also struggled with the file system everything just goes in the photos app so hard to organise.
This time I found the laptop was amazing but I traveled 15000km in an offload truck across africa and the laptop just wasn't strong enough the screen hinge gave way because of the bumps and the dust basically destroyed the screen. Managed to get it all fixed under warranty but i went to some incredibly hostile places like incredibly dry deserts and rainforests and your gear has to survive. The cameras were great and the iPad was bulletproof, now with Lightroom supporting Raw it could be a useful tool. But at the time just jpgs then I had to edit the raw again at home for better results.
I have insurance as a wedding photographer anyway but to add £5000 of worldwide cover with my home cover and £5m liability insurance it was £400 itemised but obviously the above was worth more than £5k its expensive so take what you need not everything. $15k sounds like you asking for trouble especially if your main concern is landscape. Also most worldwide cover won't let you have more than 3 months at a time. But there is a stipulation that its 3 months as you arrive into a new country.
Be street smart and you will be ok a big tripod is a big look at me sign... I took a SLR gorilla pod and it was fantastic, shot milky way etc had no issues the only problem is its a compromise but everything to do with travel it.
Also with a GPS receiver what you going to do go into the heart of gangland and get your gear back...? got to be realistic. Outside the US and the EU the police won't really care less and the police are usually involved in organised crime. While in bolivia at a train station a police officer came over to my group and we were all stood around the bags he asked to see our tickets and someone came in and stole a bag. The police wouldn't help and wouldn't let us see the CCTV so that was the end of that. Also if you have anything stolen you have to have a police report for insurance purposes. My girlfriend had her phone stolen in Kenya, we had to bribe the police to take us to the correct police station, fill out the correct paper work and stamp it. The cost was roughly 5x their yearly salary.
Be street smart and you will be fine.
3. Depending on where you are no chance with internet speeds. My 2 months across africa I got wifi 2-3 times that was usable. Even my 3 months across the US the hotel wifi wasn't fast enough even through you had to pay for it in 99% of the places. If you can get more than 1gb per night you would be lucky. I was shooting maybe 16-32gbs per day and cloud services are just useless. Get 2 hard drives of the same size say 4tb and duplicate them everyday. Then store them in separate bags.
Think carefully about your bag selection. I got the 16kg day bag on every flight as a day bag simply because it looked like a day bag. You also need a bag that is not only a camera bag but also able to take your daily essentials. I ended up with an F Stop Loka UL, you can put different sized camera sections in. I put a large on in and still had about 1/4 of the bag for storage and it took my laptop comfortably in it. Super lightweight at under 1kg which is impossibly rare for bags with a metal structure. With both bags it was still a struggle to carry both. It also has an opening only at the rear and is a self contained bag so I used Carabiners to strap the interior bag into the metal structure of the bag so if anyone did cut the exterior then they wouldnt be able to pull it out anyway. It kept my gear safe and i had no issues except the top compartment does not have its own separate section so things fall down the side of the ICU. My previous lowepro bag had a separate velcro section which was great but it only had room for one camera and 2 lenses.
There is a lot to think about and it took me a good 2-3 months and a 5 months trip previously and still got aspects wrong but its hard with so many shooting opportunities!
PLEASE PLEASE PLEASE get your visa applications sorted. We had an absolute nightmare with some of ours each country is different and some are worse than others. Indonesia for example as a UK resident we get 2 months free, but i stayed for 10 weeks. The first leg of the trip was africa for 3 months so we got into with the embassy and said can we send the passports and get a visa dated for XYZ they said ye ye send it down so sent the passports to London which is an 800 mile round trip for us and they sent it back with the date dated as it arrived back so it was 3 months out of date by the time we got there and cost £100. Anyway rang they were having non of it, had to get a visa dated within a 3 month period which we couldn't do. So we went to africa had no issues then traveled SE asia no problem. Turns out the law had changed in the time between home and arriving in Indo. We got to indo had to pay for a tourist visa on the door for 2 months when we get that as a part of our nationality... then we had to at some point get a visa booster which allowed us to be there for the extra 2 weeks. The process takes 3 days and pretty much means your in the office for 3 days I was on a trip so I didn't have 3 spare days so we had to pay an exit fine. Ended up paying £100 for the original visa non refundable, $70 for the 2 month visa on the door then we had to pay a $250 fine on exit each so for me and my girlfriend it cost nearly $1000 dollars for absolutely no reason. Please be careful and ensure you know all the ins and outs before you travel!!!
Pics removed
Cheers Tom