Read Scott's pf book at the front of this site. Very good info. Also, take advantage of the key word search feature at the top of the page, it's a real doozie, and will find everything for you in a snap. A good example would be to do a search the word icing. That will you get a lot of information for immediate use, while you wait for others to post anwers to your specic questions.
Off hand, I think you should ice when you can, and/or if it hurts, and no more than 10 minutes at a time or you may actually reverse the benefits. A rule that comes to mind is 10 minutes on, 20 minutes off. By using the search, you'll find a lot of ideas about icepacks and frozen ice bottles that you can roll under your feet.
I wonder though, in your rolly chair approach, be aware of the pressure you may be puttin on certian areas of your foot/feet, careful not to create new problems.
Good luck, feel better soon.