If I don't use the Strato II wireless. And I get one of those ST-E3-RT, it will do TTL directly to my 600ex-rt right ?
So basically these ST-E3 RT and 600ex-rt can both communicate. And whatever I adjust from the ST-E3, it will also change the remote 600ex-rt ?
I believe the PocketWizards do support RF TTL, so you can use the usual Flash menu(s) via your camera to change the power level & exposure compensation, etc.
For the flash with the Strato II you'll need to use M (manual) mode and set the power levels you want yourself. You should probably look into an intro to studio lighting class/workshop which would help you to understand a lot about working with off-camera flashes. If you buy a 2nd 600EX-RT (or RF transmitter whenever it comes out) you can then use your TTL modes & remotely control the power which can be very handy.
Instead I have to setup the light, take a shot, check it, see if I need to adjust the flash power compared to ambient or just adjust my aperture. Take another shot, rinse and repeat until done. Instead with RF TTL, you can just go into the camera menus and either change the flash power, or use the camera's TTL metering and simply adjust it's exposure compensation up or down somewhat. Much handier, but much more expensive.
Instead, I can buy 9-10(!!) Yongnuo YN-560
speedlites which have pretty good power that don't do TTL at all and just set them manually for the price of just 1 Canon EX600-RT. I'd still need to buy the RF trigger or sync cords, but a Strato II Wireless Receiver is slightly less the price of 1 YN-560, so I could probably buy 5 RF triggers + 5 YN-560's which will definitely have a lot more power (in total) than 1 EX600-RT. Or I just lower the power on all of them to 1/5 max, and then I have much faster recycle time.
So, I guess I just sorta went on a rant, but a lot of it depends on your needs and wants. If you want cheap RF trigger to simply tell the speedlite to fire, the Phottix Strato II is probably one of the best cheap ones which can be paired with decent powered, inexpensive speedlites that don't do TTL. If you want full TTL RF support, you either buy PocketWizards/Phottix Odin's (or others) along with the more expensive TTL speedlites (Yongnuo YN-565 is about $165 I think, 580EX II or EX600-RT is much more expensive) which will cost a lot more, but generally be more versatile, possibly easier to work with, and probably faster to setup & use in most cases.