I added an OWC 120Gb 6G SSD to the stock terabyte on my i7 2.3 mini. Not really broken in to anything harder than an old G5 before, other than adding RAM to MBPs. I had to take it slowly and carefully and did have to backtrack a couple of steps when reassembling to get the new SSD to seat properly but all went smoothly, nothing broke, and I now have a quad core i7 with 16Gb of RAM, a fast SSD for the system and a slower but large data drive. Which is nice.
The Late 2012 mid-range Mini (2.3 i7) ships with 4Gb RAM and the Intel HD 4000 chipset, and allocates 256Mb to graphics I believe. I have just upgraded the RAM to 16Gb (thanks OWC) and the System Report shows that currently 768Mb is allocated to graphics. So adding physical VRAM, no; the machine allocating more RAM to graphics, yes, by adding system RAM. Hope this helps. Will add an SSD to the second slot in the next week or so and the little mini should be purring along nicely. Ben