There are two-way radios that support text. Since a lot of newer radios are using digital signalling, it's not hard to add in.

Off the top of my head, any of these would work: Amateur radios that have D-STAR (connected to an Android phone), Garmin Rino, Motorola DTR, and TriSquare (discontinued, but you can find them on eBay).

Not when hiking or skiing. I always have to make sure people hear me.