I suggest you start out with the 3dsmax + Vray wombo combo. It really worked out for me. For 3ds max tutorials there are tons of resources out there on the net. For Vray tutorials i can recommend only Grant Warwick's Mastering VRay and it will be the only vray tutorial you would ever need. Most architectural firms have their own in-house renderers but more then often they do source out parts of projects to freelancers.