1) how do I transfer over my user files from ssd to hdd so anytime I install programs etc they wont fill up space on my ssd?How to move your Users folder
. This method works with any other folder you want. However, I would advise you don't do this with commonly used programs, because it's nice to get a boost. Just install the other programs you don't want on your SSD somewhere else. Windows does not get upset if you don't install things in Program Files.
Bear in mind, this has a higher chance of success the fresher the Windows install is.
2) how can i change the default install file for those programs that don't prompt you (ex. antivirus) from C drive (ssd) to D drive (hdd)? I installed my antivirus on ssd, can I uninstall it then reinstall it onto my hdd after I do the above step or is there another way or is it best to leave it on ssd?
Leave it on the SSD.
3) I will be installing Diablo 3 when it comes out. I'm trying to decide if i should install it onto ssd or hdd. Is there a major performance boost if I install it on ssd? or should i put it onto my hdd since my ssd has only 30gb free space after the installation of my OS.
The only improvement is your load times decrease.