I'm sure that some of the Belician crowd will be along soon to provide additional answers to your questions, however, in the meantime, I will just say that Belize is one of the most expensive countries (if not the most expensive country in Central America) as far as cost of living goes.
Also, while the experience on the heavy metal does sound impressive (I am not a mechanic, so I don't know how transferable to skills are to smaller aircraft), the fleet in Belize is pretty light-- Caravans, Islanders, 172's, aircraft like that.
So if you are intimate with P&W PT-6 engines and stuff like that, I would think that these type of skills would catch the attention of the local operators even more.
As far as your request for a sticky goes, I would say that a minimum income for life in Nicaragua (expat standards) would be around $2000 per month. This may sound quite high, considering that there are plenty of locals who top out at about $360 per month, however, I am talking about acceptable housing in a safe area, groceries from grocery stores (instead of going to the market which can in itself be risky business especially in Managua), having a vehicle and maintaining it, health care and schooling in a local private school-- nothing upper class, just the public system is simply deficient, a little bit of recreation, the ocassional mordida or traffic fine (just a matter of time) and perhaps some rainy day savings.