Sounds like you are talking about my bus... I don't know exactly how much power it draws, but compared to a normal house SIZE refridge, not as much. What I'm using is a 10 cu ft Magic Chef, spec's are as follows per website...
# Freezer Capacity : 2.8 Cu Ft.
# Freezer compartment : Yes
# Height : 59.8 In.
# Ice Maker : No
# Ice/Water Dispenser : No
# Maximum Amperage : 1.86 A. <================== AMPS
# Number of Shelves : 3
# Refrigerator Capacity : 10.0 Cu Ft.
# Refrigerator Light : Yes
# Refrigerator Type : Top Mount
# Reversible Door : Yes
# Shelf Material Type : Wire
# Thru Door Dispenser : No
# Two Door Design : Yes
# Warranty (Labor) : 1 year
# Warranty (Parts) : 1 year
# Weight : 134 Lbs.
# Width : 23.8 In.
I was able to run mine on my 30amp circuit, along with 2 a/c's (or one a/c and one hot water heater), or up to 3 electric heaters set at no higher than 750w each, plus various lighting, television (32" wide screen), computer etc... At less than 2 amps max it won't draw a whole lot.
As for running with the generator, most of the people in stick built RV's do that so that they can run roof air units etc... If your trip is going to be under 3-4 hours it'll keep the food cold/frozen without power for that much time.
As for mounting it, I just put a couple of brackets on the outside skin and mounted it to wall studs. I bought it at Home Depot for $299...