Hey!
1. There should be transparency in the window instead of a black colour. Maybe you lost it on some importing in Unity or something like that. Basically put it on a layer above, and under it put whatever background you want.
2.I do not have a released enemy pack yet, but I have one in the works, and it should probably release sometime this month!
3. There was recently the winter sale and my packs were on a bundle and discount then, so now they wont be on sale for a couple months most likely.