When you are drilling the hole for the lip, it probably wont hurt it any if you accidentally go too deep, just not too wide or the lips might pull away from the form during drying.

Van dykes forms are fine, they are what I use and my mounts turn out great.

Personally I dont like the earliners with bases, they just seem to get in the way. I have tried both and I like the earliners with no base.

I taught myself how to mount my first 2 deer and I watched a video. They look good. I know thy could be improved but I am happy with the results I got.

Hidepaste is different. I use dry preservative on my mounts so I use a wet adhesive. On tanned skins I think a water base is fine, but I dont have much experience in that area. Water base is easier clean up, and if you get some on the fur it usually washes out pretty easily.

Hope that helped some. I am a beginner also, so if I am wrong on some things I am sorry.