1) - a work collegue with a Fatman loves it.
2) - dont know anyone on the forum with a Roth Cocoon, or even the Fatman, so suggest you do searches for both on the whole Whathifi site to see what is there. The Fatman is well rated.
3) - using an ipod as a source to be plugged into an amp is perfectly acceptable (to me and others, but many disagree!). The advantages of separates are the ability to upgrade one part at a time and to move to a PC based setup where instead of the ipod as the source, it is itunes on the PC. The PC feeds a DAC and the DAC feeds the amp. This produces excellent sound, better than 1) and 2) I am sure. But 1) and 2), depending on space and convenience will also sound excellent.