I haven't towed with a Vitara though I have done a lot of towing and have driven a Vitara so my guess is...
ok for something that sort of weight though I wouldn't tow a heavy load as the Suzuki engines don't have much torque at low revs so a smoky clutch will put in an appearance fairly quickly
4WD system is a basic part time 4x4 system on Vitara as I recall, so ok for getting up a slippery slipway but you can't use 4x4 all the time on the road like, say, a Discovery where 4WD is permanent.
Suzukis in my experience ARE reliable - very - but like most things you get to "a certain age" and then start pouring money in to them big time. Just don't buy one "of that age"... and "that age" is hard to define.