Questions about IMAC and PT 11

I am about to purchase a new 27" IMAC which I believe will come with Yosemite OSX.



The machine will have:



4.0 Ghz Quad core Intel I7 with boost up to 4.4Ghz

32 GB RAM

3 TB Fusion Drive

AMD Radeon R9 M295X 4GB graphic card



Questions:



Are there any known issues with this type of MAC set and PT 11 running on Yosemite?



What do people mean when they suggest having a dedicated graphic card and what are the advantages and how would I do that?



Would the machine operate better with the 1TB flash storage MAC option than the 3TB fusion drive?



I appreciate any help. I am intending to purchase the UAD Apollo interface quad core.