New Kegging Setup Upgrades

Unexpectedly, I found a good deal on a keezer on Craigslist and am now jumping into the world of kegging. While the setup I bought is in good working order, I'm looking to make a couple of updates before I get too far along.

First, I'm planning on replacing all of the lines and putting on some drip trays. Easy enough there. The keezer came with 2 ball locks and a 5lb CO2 tank with a dual gauge regulator. I know I'll need a manifold, at minimum to use both kegs, but I'm looking at my options. I could replace the regulator with a dual body or a secondary regulator, as well. If I go with a secondary, does that install where the HP gauge is on my current regulator? If so, would I lose that gauge? If I just go with a manifold, and I wanted to force carb a second keg, could I shut off the manifold to the already-carbed keg, turn up the regulator, then open the manifold again once I lower the second keg back to serving pressure? I know I'd be without access to the first keg for a day, but I could probably make that work.

Second, while the keezer only has two taps, there's room for 4 kegs inside. The current faucets were drilled through the front of the chest freezer (a 7.0 cubic foot GE). Even though it clearly worked, I'm assuming that drilling more would be a bad idea. I could add a collar (and probably will), but in that case, would there be any benefit to moving the existing faucets up to the color? Would having two levels cause problems (aside from aesthetically)? If I did move them, is it possible to plug the shank holes in the freezer?

Finally, the faucets installed are pretty cheap. I'm looking to upgrade them to Intertaps or Perlicks. Are there other options I'm overlooking? Also, is flow control worth it? Would they make it possible to serve at a constant pressure but emulate other styles (like less foam for English ales, etc)? I'd seen that mentioned somewhere, but I'm skeptical.

Since I wasn't really planning on jumping into the keg world yet, it feels a little overwhelming at the moment. Any help with the above (or anything I may not be thinking about) is greatly appreciated!