Welcome, Greg32433. I’m not sure there’s a good free mp3-to-midi converter out there. If there is, I’m sure somebody will weigh in with their recommendation. I’ve seen commercial versions but I can’t vouch for how good they are.
Have you searched the Resources section of this forum for the songs you want? If they’re not there, refer to this link for posting requests to the forum: http://mybeatbuddy.com/forum/index.php?threads/when-asking-the-forum-for-a-song.6030/
Although many BeatBuddy (BB) users prefer the flexibility of the traditional formatted (verse-chorus-bridge) BB songs, it requires more effort to assemble so you’ll find that the majority of songs going up in Resources are one-press (OP) or one-press with bass (OPB). To use OP and OPB songs, you will need the latest beta of the BB Manager, which you can ask for here.