There are no scheduled flights from San Ignacio to Belize City or San Pedro. You'll need to take a bus (US$2.50-$3 per person), van (US$25 per person) or taxi (US$80 to $100 for up to four or five) to Belize City, or of course you could drive, and then fly to Ambergris Caye.
Best to fly from the municipal airport, as fares are from there to San Pedro are one-half the cost of fares from international.
The San Ignacio Resort Hotel is okay. It's a little pricey for what you get (cinder block walls) but the location is convenient and the restaurant and bar are good.
Belize First http://www.turq.com/belizefirst/