Here is the compatibility list
I am running everything from internal as I have a 1TB hdd in my PS3. And I don't have that many games here to fill the whole storage.
A good tutorial for the conversion was pretty hard to find, as there are way too many tutorials and every single one is doing something different. I've used CFW2OFW Helper which did the job perfectly for me. Btw, it is relatively easy to se and also checks if a game is compatible before converting it.
Edit: Btw, now where I do not need webMAN for iso games anymore, I am using it to permanently disable cfw so I can directly go online. As long as you don't really use homebrew that often, it works great. And if you need to use anything homberew related, just disable wifi and activate CFW in the webMAN settings.