Aw, this reminds me of my guinea pigs. The last I had died two years ago at the ripe old age of nine and a half (having outlived her companion by one and a half years) when I'd already gone to uni. I'd love to have two of them again, but that's something I can't do in student accomodation.
The noises they make are really cute. When I took my last guinea pigs inside because one of them had rheumatism, they figured out that the sound of the fridge opening in the nearby kitchen often meant food, so they always started squeaking as soon as someone was rummaging around in the kitchen. I'd love to post some pictures of them, but they're all on my old computer.
With my guinea pigs, their favourite food varied a lot: One really liked red peppers (not green or yellow, though), one loved chicory (although it would get diarrhea if we gave him too much) and the next two were so spoiled they wouldn't eat things we fed them for too long anymore, except really fresh young salad. Of course, these were more like treats; the bulk of their food was hay, carrots and grass in summer (though also not too much of the latter).