Digging into the TalkBack settings, you can have your phone tell you what keys you're typing, can speak when the screen is off, speak caller ID, "touch exploration", and a lot of other settings.
Yeah, so I just tried that on my Razr (Android 4.1)....telling you what you pressed after you pressed it doesn't really help find the key
icon in the first place. In the accessibility options, I can enable "large text" which roughly doubles the size of all text and icons. You can also go into display settings to set font size to "Huge" which does basically the same thing. That would be pretty helpful I imagine.
Regarding the dial-pad, my phone's dial pad takes up the entire 4.3" screen, so that's a non-issue.
Besides all that, choosing a plain/colored background that contrasts well with text and icons on the phone is a must. I don't see an "inverted colors" option in my Razr, so if I select a white background, I can barely see my icon labels. Dark/black backgrounds provide good contrast to the white letters though and will reduce battery drain.
Main: i5-3570K, ASRock Z77 Pro4-M, MSI RX480 8G, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, EVGA 550-G2, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Crosley D-25 Case Mod