First off, I think that any site that you create should be completely separate from PO. The main reason is so that you don't run into any legal issues within the US as far as online poker legality or any future bitcoin restrictions. However, you could copy quite a few PO features onto a new site. Ideas would be if you setup a separate bitcoin loan shark/marketplace/staking system. Instead of completely anonymous, make users do an id verification before using any of those added features. You could indirectly connect the sites just like you work with other sites for redeems, freerolls, promos, etc.

As far as software goes, as you stated, your current software will work. It's a good option if you don't find anything better. The only other option I can think of it to try and track down the owners of the pokerdominicano/freedom poker software and try to buy that. It was good software, but you would be dealing with some shady people that are hard to pin down. Another option would be to look into developing your own software. Start with your current software and if you're profitable, re-invest the money into the development of new software. Something to keep in mind is having a way for mac players to be able to play and for people to play on their phones/tablets.