I don't have my copy of FR with me but if I remember correctly it was +1, and there wasn't a mininum level....but then again, I don't know it for sure...
K: why do you say what you said, I'm looking at my FRCS and it says Level Adjustment is +2 and must have at least 1 hit dice (page 288) was this errated? For some reason 5 levels ECL 5 is sticking in my mind though