1. If those 6-10 websites is all he uses, may be switch to some tablet and create shortcuts for those. If you are up to it, jailbreak the tablet and change the UI completely which has customized fonts, icons/shortcuts.

2. For email, use Gmail as it seems to be the current best w.r.t. filtering. You should keep access to this account as well and check yourself from time to time. May be increase spam setting to max, to lean on false positive side.

I feel that this whole technical revolution of last 2 decades has really left out all elderly, not just people with medical conditions. What is needed, may be, is a generic interfacing layer which can map any app's UI to simpler interface and yet maintain core functionality of the app. I dont know if there is any, or if it's even feasible.