glasswill this interfere with my current hud/cfg? should i take steps to reconcile them?
It won't do anything with your hud or cfg, this doesn't touch stuff like that.
sibbydoes this still require preloading?
Some of the model removals do, but the main ones don't. Player gibs / ejected shells / weapon gibs do, but nohats doesn't and everything else doesn't.
The big thing that required preloading in the old cleantf2 -- the unlit textures -- are considered "obsolete" in this version because tf2 updates stopped it from being preloading and it's very broken in sv_pure nowadays. It can still be enabled by going into the generate.bat and editing it, but I wouldn't recommend it.
I can't add screenshots until later tonight at least. Most of it should hopefully be pretty self explanatory, except for how flat textures works (sv_pure 0 is the same for both, sv_pure 1/2 looks default with unresized flat textures, and sv_pure 1/2 with resized textures looks like this but with lighting).
There are also some more things I need to list out to make flat (models, mostly) but that'll just be a few lines added into a file.
ivan_does the cleantf2 still break in sv_pure
Yes and no. Flat textures will either return to default (if not resized) or be grainey (if resized) and that's down to preference (I actually prefer the grainey to default, though I know I'm in the minority there). Everything else should be fine.
Breaking as in "some textures are fully lit, some are completely dark, and some are missing entirely" that you'd see with unlit in the old clean tf2 will still happen if you manually enable unlit textures, but you have to go out of your way and edit the generate.bat to do it.