Just the five obligatory prayers plus witr for Hanafis. Yes, "converts" or born-Muslims have the same Shari'ah. They should be encouraged. For evidences see the articles below; for the method, Fulan will just have to pray the same exact prayer(s) he missed, with the intention of "making-up a missed prayer", plus making tawbah. If they didn't start the fast at all, they will have just to make-up the missed days of fast (29 or 30); the kaffara is for when one breaks his fast after having started it, not for when one doesn't start it at all. There is also a fatwa by Mufti Muhammad Ibn Adam al-Kawthari on Sunnipath about this.