It has been a long time since I've created my last D2 level. Now I have a new one in the pipeline

Question 1: I would like to use custom textures for this new level. Is there probably a collection of textures for D2 somewhere a level builder could use?
Question 2: What tool do I need to create a POG file? I've done that once, but that was years ago...
Question 3: D2x-xl supports high-res textures. Is there a page where the specs are listed? I should know things like size, color depth, probably alpha channel info.
Many thanks for your help!

SnyTek