Buy some of these (check the "wood floors" and the "wood boards") and you'll be a happy man. You will receive as a gift some nice scratches&dents bump maps.
be aware that using displacement means that you are asking vray to subdivide your faces for you if they are something other than quads (more than 4 vertices per face.) You will see such triangulation artifacts if you are not careful to draw interior lines so you end up with more "square" planes on your face.
There been some suspects that if both vray for SU and Thea for SU are installed there is change for a crash (maybe observers do not play well). Anyhow... about the crash, you really should post a detailed bug report at Thea forums (if you not already have done so); used software version (su, thea & vray..., os, hardware specks, gpu drivers and so) so that Tomasz can take a look on this. http://www.thearender.com/forum/viewforum.php?f=82
The weird thing happened that my vary proxy item turn transparent in the render image.
I though there is no way to edit the proxy item in the vray material editor. Since the proxy is just fragmented polygon floating in air. It will be nice if it's true.
I was supporting your statement about OBJ. OBJ is my preferred format too. I've imported 3DS before and it often contains too much geometry and takes longer to import compared to the cleaner OBJ version. 3DS often has errors too, as you clearly illustrated above. π
If you see it stall out like that, it's likely that the XMLDRSpawner is frozen or has crashed. This needs to be running in the background, in order for RT to work properly. You can check that by looking in the task manager on Windows, or the activity monitor on OSX. I would suggest killing that process and then running it again, just to make sure that it's not frozen.
Actually, If you have SketchUP 2014 (or an educational version), you can purchase an educational trial of VRAY for SketchUP from Novedge, here: http://www.novedge.com/p/8841
It's $138, compared to the $700+ commercial version.
I'm not saying there's no workaround - it's just that this effects regular groups in a model, not just when you make a proxy. I think best practice when modeling is to not add material properties to top-level groups, only low level groups or faces only.
In my very honest and humble opinion, 1.49.01 is just not a great rendering plug-in. 2.0 and moving forward is where you want to be. Stop killing yourself with that bug-ridden version and update as soon as you can!
You can definitely try what njay suggested, but it would help the community to know what version of Vray you are using as there have been bugs in earlier editions that have since been fixed.