hi there we own a 1995 rav4 swb and a swb defender, the answer to your questions is
all ravs are full time 4x4 (although i think they made a 4x2 version)
there is no transfer box so no hi or low box
most earlier models had manualy locking centre diff not sure about later model
they have a monocoque chassis
they are very competent in snow and in mild off road conditions, but i would not recomend for serious off road use the lack of high low ratio and bits hanging down do limit it, but they are super reliable nice to drive and do around 30 mpg (petrol) its a case of horses for courses, if we go off roading we take the defender, but normaly we take the rav knowing it is its reliable and will takle snow, muddy show grounds etc is great fun to drive and will not let you down
