Custom ROMS, OEM's, etc?

[BlackDynamite]

First off- this site is awesome!

Okay, so I have been reading a lot about how to cook your own ROM, and the various discussion threads about all the custom ROMs people have created. I have a few questions though...

1: What do you need to do with the OEM folders (each individual app) on the ftp? Do you just drag them to the OEM folder on your kitchen? Do you need to do anything else with those?
2: What is the difference between all the MMS OEM folders? Is one of them better for Sprint?
3: When putting your apps on a custom ROM, does it save memory or storage or something? What is the benefit to putting it on a ROM over just installing everything manually and then making a backup file?
4: I'm still running ROM version 2.06.00. What has been fixed (or made better) with the 3.5 version? I'm still trying to decide if it's worth it to upgrade.
5: What's going on with a WM6 upgrade? Any word on when we might be able to get that (on another board they were saying MS has already released it to HTC)?
6: There are a few MS Live OEM folders- is one of them the Live Beta (the new Pocket MSN) or are they all the Live Search thing (the one that's kind of like Google Maps)? I just uploaded the Live Beta (the new Pocket MSN) to the apps folder here by the way.
7: Based on my app list (below) is there anything else in the OEM folder list you think I might find useful?
8: Anything else you think I might find helpful? I've basically already read the tutorials and threads on how to create your own custom ROM. I'm just asking the questions that weren't really covered in those threads.

BTW- in case anyone is wondering, or needs to know what I'm running in order to answer my questions, my device is a Sprint PPC-6700, with the following:
ROM version 2.06.00, ExtROM version 2.06.300 (and I took the junkware out of it myself back when I first got the device, thanks to instructions on this site), Radio version 1.12.00, A2DP patch installed, MS VC over bluetooth hack, Sprint MMS patch. And the software I run is: MS Voice Command (1.5), PocketCalc, Adobe Reader, Flash Player, Card Export, Resco Explorer, Sling Player Mobile, Spb Backup, Spb Mobile Shell, Google Maps, Live Search, MS Live Beta (the new Pocket MSN), Total Commander, and Griff.