#1
I recently just bought myself a VoxVT20+ amp and it has and audio out cable in it. So I hooked it up to my computer and it plays perfectly it makes it fun to have a virtual drummer with me.

Is there anything better then Monkey Machine though? It sounds alright but I kinda have a feeling there's tons of shit out there that's better.
#2
i dont know of a program like that, but i used to just download drum tracks and play along. you can get tons of them from a program like Soulseek. some will suck, some will be fun, but you can get a good variety of them
#4
You should try downloading a software like amazing slow downer, which removes voice from songs, and you can also slow down the song.

This way you can just select your favorite tunes and just play with the rhythm section/

Personally i haven't used drum machines.

You could also try guitar pro and write your own drums there .