Regarding the extra inputs you mentioned above (the 744T only has 2 pre's on board), in case you haven't solved that, you can buy or rent a MixPre. These 2 will match well. This is better than C-Linking 2 units. Though, if you already own a 702, then.....
A better solution is an SD 552, which you could probably rent. Just use the pres on this, get cables, set the 744 to Line In and .... (Though, you could also rent a 442). The 552 is an amazing feat of engineering in how much they packed into a box that is lighter than the 442. You can do IFB, camera feed, isolated boom-op feed with talkback, another separate feed to the video assist or video village.... So many options on this thing.
For batteries, as Charles says, the big Sony batteries last for hours... Look for a FP970 or its "replacement". A google wil reveal inexpensive suppliers in your area. But, for when you have a Mixer, or MixPre and Wireless.... I'd look at getting an NP1 with a battery distro box (Like a Battery Bud, great for bag work). Then you can power your mixer and wireless all day and keep he 744T on its internal. IDX is a great option for the U.S., and I believe that Hawk-Woods is more standard in the UK and Europe.
Hawk-Woods Ltd for Broadcast Camera Battery Systems/Chargers/Adaptors/Batteries