First of all, can I commend you in your approach to this, because what shines through in your posts is your willingness to keep the DCs' needs uppermost.
Some friends of ours have an arrangement like this and it seems to work very well indeed, despite a hugely acrimonious divorce after infidelity. Slightly different arrangement in that one week, the split is 4/3, the next 3/4 and alternate weekends, so that both parents get to be with the DCs during the more relaxed nature of weekends. This is only achievable because both parents altered their working hours and live within a 5 minute drive of eachother.
On the DCs' birthdays, both parents have a protected chunk of time with that child, regardless of the rota. Christmases are alternated, but again both parents get to spend a chunk of time on the day itself, achieved by alternating Christmas Eve sleepovers.
There were hiccups along the way because initially, feelings were running very high and there were some arguments in front of the DCs on handovers. However, although the parents still can't stand one another, they communicate about the DCs via E mail, for the reasons mentioned by an earlier poster.
This won't affect you just yet, but the DCs I'm referring to are older, the eldest being a lad of 16. As you'd expect, he wants to do his own thing now at the weekends especially and while his Dad understands and supports this, his Mum guilt trips him if he doesn't want to spend time with her when she sees him, so although that's a long way off for you now, bear in mind that the DCs' social needs change over time and just like a conventional set-up, they get to the healthy stage of not needing their parents as much.
Good luck!