So if I decided to buy an Android app. 1 how would I know. 2 is sideloading automatic or do I have to do a bunch of stuff to run an Andoid app?
The ones in app world you don't know for sure... Although the screen shots sometimes give them away, as do some of the app developers/distributors (eg Handster). These will install the same as native apps from app world, but will launch on the android player.
The sideloaded ones are apps individuals have converted and posted for all to use - these need sideloading (which isn't hard tbh). These will also launch in the AP.
It's a part of the Android player support, don't touch it. The PB actually doesn't let you delete it even if you wanted to. It doesn't take any space, just consider it a system thing.