I have a R4 but I'm running 2 2.5 hhd on it and a ssd.
I need more space because I take a lot of RAW pictures and video, I'm thinking on taking the hhd tray out and putting everything behind the motherboard or get an external driver solution.
ideas?
I would put the SSD behind the motherboard tray since it is vibrationless, and put the HDD's into the HDD cage. now if you use the information on multiple computers, then a networked storage configuration could be a good way to go. If you really only use it on that one computer, then I would just leave them in. HDD's are just one of those things you can usually forget about until your next upgrade.
what external hard drive cage and hard drive to go with it do you recommend?
You could make a nas: http://www.youtube.com/watch?v=e1n3rHlUY3k
or you could buy one: http://www.newegg.com/Network-Attached-Storage-NAS/Category/ID-241
As for which device, it is hard to say. It depends on your needs. If it gets into the hundreds of dollars, I would recommend building one. Teksyndicate also has a video on how to work the software.