aminbakht

for single frames it always did. Do you mean for add to current map etc?

seems like you have flipped normals on and they are interacting with some objects inside that are intersecting.

VRay sun seem to be a faster option rendering wise. If you are using an HDRI in a dome light the render times will be much higher. For me personally it depends on the kind of lighting I am going for that dictates which option i use. But I know some really good artists just use dome lights with good HDRIs to light their scenes. I guess there is no better way in this case, just a matter of preference.

I have only used http://www.rebusfarm.net and had a good experience. Fast renderings and good support. I used it on projects where we used maya + Vray and maya + Arnold. never had any issues. Though they felt a little expensive but I never used anything else to compare with.

lol. I would be interested to know what their reply would be if you actually asked them for it!

I would recommend what Hooman said as well. It seems that architectural modeling and importing of cad data is more streamlined in max. If possible do it in 3dmax and then export to maya. That is what I do.