No, the FFC adapter board is oriented correctly in the first picture. Just wire all the grounds from the adaper board to a common ground. Ground is ground is ground, it doesn't matter where you get it from. #.43v can be taken from anywhere on the board that supplies it, or just take it from the regulator like you said.
To answer some of your previous Q's, You're going to want to use Li-Ion/polymer batteries. I recommend Li-Ion because of heat/safety concerns of Li-Po's. But if you have a roomy case and can keep the Li-Po's away from other things that are sharp/produce heat then by all means pick your poison.
Which brings me to the regulator. Seriously, unless you're on a super tight budget go for a custom regulator setup:
http://forums.modretro.com/viewtopic.php?f=36&t=2844 It'll allow you to run off a 7.4v Li-Ion setup, not to mention it makes managing space and battery power much, much easier. If you're hellbent on going with the original regulator, go for a 14.8v Li-Ion setup. The stock regulator will take up to 30v and chug along happily. Nintendo sure knows how to build rock solid machines.
Pretty much all of those "reversing car monitor" screens on e-bay accept composite and will run on anything from 5v-14v. I recommend getting a 5" one. you get the most bang for your buck IMO.
As for audio, there is nothing better than these babies:
http://www.ebay.com/itm/Mini-Portable-A ... 8783198060 and a set of DS Lite speakers to go with it.
