ive had a sav for almost a year now so i have a bit of knowledge in the subject
yes a 6x3x3 cage is not only big enough its what most people recommend for a sav so you hit the nail on the head so to speak.
funtion over form. however that doesnt meant your setup cant be nice looking, or natural for that matter...just make sure its got a hide spot or two and stuff to climb on and dig under. unfortuatly they dont sell pretty hide caves for big lizrds but you can always make one...just build a hide from plywood, cover it in plaster to look rock like, and paint it gray...looks very good if done right...if your too lazy to do that im sure you can figure something else out...just remember it doesnt have to look pretty for tha sav to like it...it just has to function. a crappy looking plywood structure is just as good to them so do what you want on this topic...the lizard wont care...you will.
as far as your buddies lizard its isnt a determening factor for sexing it...and although im not much on lizard gender i believe female can pop a hemi-clit or something like that...the hemi-pene on a male will be somewhat large and look nobby at the end...proexotics has a pic of this somewhere on their site www.proexotics.com.
and just out of curiousity why do you wany a sav? i started out with one and hes a complete pain in the ass (mind you i like my savanah and hes very entertaining at times just watching him)...i dont mean to bash them cuz ive run into people who have some really tame savs, but alot of them are just plain b*tchy and difficult to handle...i mean as far as ive seen your chances of getting a sav that refuses to tame are like flippin a coin, so if your friend has a decent one that doesn't nessasarily mean you wont have a little monster on your hands...just a thought, there are ohter monitors outm there similar to savs that have much better dispositions, like blackthroats...but hey if you really want a sav get one, and have fun keeping it but i dont recommend them to poeple who havent had monitors before. then again thats your call.
well i think those were your questions....if i forgot any ill just make another post. take care and if you decide to go ahed and get one have fun...thats what its all about anyway right.