I'd like to rip the Darth Vader model from the PSP's imp.lvl but don't exactly know which parts to look for. I see certain bits that begin with skel or modl and am wondering which do I need, and is there anything else to get as well? Thanks!

i cannot find it, but there is a website that explains the msh format. Maybe it helps you to find Darth Vader's structure in the lvl file. It was ZETools http://schlechtwetterfront.github.io/xs ... /#overview or the secreat... googlepage

Find the model's name in the lvl file and there should be an IBUF and VBUF chunk nearby that will net you the geometry and UVs.
You can convert that data back to an obj or something using Hex2obj from Xentax.

Riley-man thoroughly documented the data stored in lvl files, have a look at the Model Chunks htm file.
viewtopic.php?f=64&t=27255

Can't find IBUF and VBUF near anything related to Vader. In fact, there are no results at all for IBUF and VBUF in the entire file. I am guessing this is because the files were made on the PS2 munge platform, or that the original models were not built the way they are for PC.

Okay, for PS2 lvl files it looks the same but with different chunk IDs.
You are probably looking for POSI (possibly vertex block) and TEX0 (looks like face indices), there is a NORM chunk between those.
It looks like each 4 byte chunk ID is followed by the 4 byte chunk length.
The model data also looks broken up into multiple segments (segm).