What adjustments would I need to make if I were to tune down to C standard, and put on heavy (up to .54 or .56) strings? The action? What else could be adjusted for maximum comfort? When I tune down now, my strings tend to rip and break off at the bridge more frequently then I think they should. Is there a fix for this?
The action would probably have to be adjusted, either through the truss rod or bridge height. intonation may have to be checked over as well.
Possibly nothing. Besides intonation of course, but that's normal.

It helps if you understand what is going on on your neck.

Your strings pull your neck up toward them. Your truss rod is there to keep your neck straight. It's purpose is to exert an equal force opposite to the strings.

Your tuning determines your tension - raising your tuning raises your tension, and vice versa.

Increasing your string gauge increases your tension, and vice versa.

So when you lower your tuning (tension) and increase your string gauge (tension), you're going about things the right way - ultimately the goal is to keep your tension in equilibrium. Raising one and lowering the other means that you shouldn't have to adjust much, if anything.

As always, your guitar will not immediately explode from doing anything - just swap the strings/tunings and see what happens. It's never good to get uppity where the truss rod is concerned. Only adjust it if you can actually see your neck bowing, or if you're getting fret buzz in the middle of your neck. Otherwise, leave it alone.
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