Two-player cooperative game format
Two-player cooperative game format
You can purchase a single copy of Borderlands 2. Using one Steam account should let you play both games on multiple machines. Co-op via LAN is possible with a single account. Disconnecting from the internet might help in some cases. For comparison, BF3 on Origin supports a CO-OP mode with one account.
Yes, you can achieve split-screen co-op using a console command in BL2.
Not FPS but I will always suggest Resident Evil 5, it's great in co op. Also might wanna consider Splinter Cell Conviction games if you ever feel like switch genres. Dying Light is awesome. Heard Killing Floor 2 was fun.