As you've noted: in quick-loading, pac is used --- otherwise pcs is (since pcs has to take extra time to be decompressed) If you can figure out how to swap which loads based on a button combo... sure that will work.
But that would probably require a PW level code maker --- have to essentially change the game's programming on what it loads / when.
There are a few awkward things about it... but you get used to them. Hell, I got so used to the "Ctrl+K" to delete that when they changed the hotkey to just "delete" I immediately changed it back.
Hope that helps ya out! Also... I keep track of my own texture download stats...
http://www.kittycorp.xtreemhost.com/?p=662 (Not including stuff since I've moved to media-fire, madworld ganon currently leads there at ~200 new downloads while Jetterz Daibon trails at 10)
I have roughly 99 character textures right now (all with CSP's), 10 stages, 1 asist trophy, and have no issues. As far as CSPs go... I have heard that over 100 will cause issues --- but this is a CUPASH bug. I don't think there is really a limit... freezing is often a result of a bad file / SD card.
As for common3... that is items, no? There isn't a quick way of doing this. Using SSBBarc (instead of manual hexing) does speed up the process a great deal (as it does support adding of multiple files)... but no there isn't really an easier way yet.
Although (I never have seen this myself) I've heard that the sound issue might be caused by out of region files. Since these files contain sound info... using NTSC files with a PAL brawl may have some issues.
This will reduce the color count (and therefore the filesize).
Also... "reducing complexity" may help. A single color image will be a smaller file size than a checkerboard pattern, and a checkboard pattern will be smaller than random "static".
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STASH works best if you edit one image at a time, repacking after each. Many stages contain at least 1 "huge" image that you can apply either of the above steps to and give yourself some "leeway" with modifying the rest.
Yeah, that's exactly how they work. But... go and ask the guy who made the textures --- I believe he did mention that he accidentally removed those effects you mentioned.
No. Read the FAQ --- there is a section specifically about transparency.
And both those are basically specularity --- that is... the "shine" of an object. Basically... you can shape it / dim it. Additionally, the spec texture of his defines how much lighting his outfit recieves --- allowing for the appearance of smooth / rough segments.