wrt to veg - have a look at another thread running right now - most of the details are there, but basically, lob it in and go if it's a 2.7. If you get a 3.0 then strictly diesel only.
Rust is normally found where metal once was!
Main areas to concentrate on (although all fixable with a welder) are:
Seat belt mountings in the rear wheel arches - classic MOT fail point, easy to see and poke to test for strength.
Main rear passenger seats, lift them up and peel back the carpet - often the point where the back outside edges meet the floor is more like a ferrous oxide aero bar than steel.
Front lower cross member under the radiator, easy swap out for a chunk of box section or angle.
Inside the front wheel arches, peel back the rubber inner liner and check the front chassis mounts right behind the headlight area - can also be rebuilt - more fiddly.
Certainly on LWB ones, check the very back corner body mounts too - wear a pair of goggles, as rust flakes in the eyes are not nice!
Inner wings can go too, often find on older models a plate or too has been done here already.
Sills - front and back inner and outer tend to crumble away, no simple repair panels available, but inners are flat sheet anyway and outers can usually get plated up. If you prefer the more rugged look, a few members have just replaced the whole section with 80 x 40 3mm box section instead.
Chassis are normally fairly good on these and are mostly quite easy to inspect - one that's spent it's life launching boats will probably be knackered though.
Front wings are bolt on and are not structural so shouldn't cause major MOT issues - they all go from behind where the plastic trim fits and builds up crud over the years. The same area on the rear wings can go too as the plastic trim is there as well.
That sounds like a list of horrors, but if you can get a clean one and waxoil or whatever to protect then they'll last for ever. (cue Rustic with his original 18(?) year old truck.....)
Have I missed any bits ladies and gents?