pricing and other dummy questions

I have 2 cpu server where I have bought 2 cpu licence. To have 2 node HA I need another 2cpu licence I guess?
I do like 2 node HA instead of 3 node HA so can I ?
1. run software raid on 2 node HA?
2. can I deploy 2 more dedicated servers with two node HA and then have proper quorum? or? I am bit confused with 4 dedicated servers both on 2 node HA :)

Thanks a lot for clarification.
Regards!