With all due respect, if you don't know what difficulties you might get into I would recommend you get the engine running first, unless you can get somebody quite experienced to come along. Sailing without an engine will, however, make you into an expert boat handler. You just have to avoid running into anything dangerous or expensive.
While I'm here, I am really paranoid about gas inboards. I would rather have an outboard if I couldn't afford a diesel.
Sail Fast Live Slow
40' Norman Cross trimaran