[jacksplat]

that's a tall question. A ROM affects *all* of those. Each ROM has various tweaks and versions of windows mobile OS. They can have any number of of default programs or exclude some junk you may need, plus added applications that you may find useful.

As far as touchflow 3d...you must mean 2D (as 3D doesn't run on our phone), it's nice, but it does take memory and if you dont' really need your today screen decked out, then I guess it could be a memory hog.

General rule: if you are going to try flashing your phone, don't be overly attached to your data. Like my signature says "one more flash..." You may find something you like right away, but almost always, you will become addicted to chasing down the white whale of a perfect rom.

You need to determine what works best with your daily needs. if something slows your phone (i've had tons a ROMS that I flashed and didn't like), then move on.

Like I said...tall question.