Heat does not hurt colloidal/ionic silver at all - though cold temperatures will make the silver particles agglomerate (clump togethter) and precipitate down to the bottom of the solution.
Adding iodine should be no problem - though you might want to play around with the amounts, as it could cause some skin irritation in larger amounts. As a matter of fact, the skin cream I like to make contains greatly condensed colloidal silver and oleander extract as well as some iodine and a few drops of DMSO. Works great on all kind of skin things - warts, moles, age spots, pre-cancerous lesions, skin cancer . . . though one must be patient, as it does take time and consisten daily applications (two or three applications a day work best) for many such things.