I agree with papa razzi. You should definatley sell the 35 and get the 24-70 II, but it may be necessary to get the 50mm f/1.4 or even the f/1.8 for those low light wedding situaitions when you absolutley need the f/1.4. However,the 5D III and its lowlight capabilities may be perfect with the f/2.8......... you just need to decide what you need.
Really? I guess it's just me but I find the 50 1.8 to be a good lens for the price but trying to use that as alternative to the 35 1.4 is a bit crazy in my head. Take a look at some charts and you'll immediately see these lenses, or for that matter any of Canon's 50mm lenses, are no where near what you can get with the 35 1.4. Not only is it sharper but I wouldn't trust just having the 50 1.8 as my low light lens for a wedding. Perhaps something else that it doesn't matter if you miss focus but a wedding. People pay good money for a reason, they expect you to be able to get the shot.
Now regarding whether to get the zoom or not, everybody so far seems to have only good things to say about it. Here's my thought though. Unless you really NEED the lens right now you're much better off waiting. The 5D mark iii launched only like six months ago at $3500. I just saw it the other day from Adorama for $2750. With these products, I think Canon realizes there is a pent up demand and that people are willing to pay the high prices to be first to get it. If you're willing to wait, at the very least they'll be having rebates on it and most likely a combination of that and a slight reduction in price could easily save $200-$400. That's just my thought. One alternative that would be much cheaper is to keep the 35 and get a 24-105 instead. Sure it's not quite as sharp but if you look at Roger's numbers from the comments section of his post on the new lenses resolution you'll see it's not that bad (835 / 820). This would give IS as the wide end which is great for a shots of the venue or anything else that's not moving. Plus add more reach at the long end. This lens has been out for a while so you're paying the premium that users of the new lens are. Sure it might not give you euphoric high of getting to play with the latest and greatest, but I think it would serve you well. I routinely see it for $800 and that's about what it's going for used as well so if you find you don't like it after 6 months to a year, then sell it and perhaps the 35 and go buy the 24 70. Chances are you'll have a better idea of what you're looking for as well after you've had a chance to try image stabilization on the wide end.
WHOOPS just looked at your signature. You already have the 24 105. My bad. In that case my same logic remains of waiting. But of course it's your money and your equipment.