Perhaps you have WoW-modifiers enabled in ISBoxer and your main character happens to be the [Shift] character? Then IsBoxer would add [Shift] to all your 1-9 key presses.

You can set up a keybind to switch to another character if you die. I mouse-click on a character window manually, though (via a picture-in-picture feature). Or just drag the mouse over to the monitor on another computer. My assist macro in Rift uses the [shift][ctrl][alt] modifiers so that all characters can assist whoever I currently use as "main" character.

In IsBoxer, you can set up a sequence for a key. Every time you hit that key it'll do the next action in the sequence. I don't use it myself, but you can set things up so that if you press 'A', it will first do one action on your action bar in Rift. Then you press 'A' again, and it will do the next action on your action bar. I think the in-game command /castsequence worked like that in WoW.