Lots of good questions - here is a cut at them (midwest centric).

How do you protect yourself from possible physical dangers (falling debris, fires, etc...)
Have a plan for the scenarios appropriate to your area. Know where the fire exits are, look for strong/weak points in the local structures. Running outside in an earthquake or tornado is an iffy proposition. Luckily the earthquake is a real low order of probability here.

How do you find your family?
Head home, then for the kids school. The wife and I have out of area contacts, the kids aren't quite up to that yet.

How do you get home?
Walk or drive - I live less than a mile from where I work. If the roads a unpassable I'll go cross country.

How do you find aid stations?
Aid stations tend to set up at the local fire stations and medical clinics. A couple of those are on the way home. Last major "disaster" around here they also setup in the Walmart parking lot (about 5 miles away). The national guard keeps a bunch of stuff about 15 miles away from me, near the local airport, also.

Will you be able to get news from radios?
Maybe - depends on the disaster. Local AM might have some info if available, regional AM is more likely (WHO carries a long, long way at full power).

How can you tell if you've been exposed to radiation?
No reliable method for me. Listen to radio and assess likelihood is best of bad choices. Giant flashes of light and mushroom clouds would also be a clue. Reality is I'm more worried about a "chemical" accident than radiation - like Anhydrous Ammonia.

What will happen if you are exposed to radiation?
Depends on how much and what kind. In general get out of the area and decontaminate (wash down) and drink lots of fluids to flush your system - Beer is great for this. For low doses, probably no short term effects, for higher doses expect some form of radiation sickness (at least nausea and weakness). With a really high dose set your affairs in order quickly (if possible).

When will "help" arrive (I know this is a potentially loaded question)?
Amateur help will arrive as soon as imminent danger is past, if not sooner (love the midwest for that). Local professionals will be swamped if there is widespread damage and injuries. Need to plan to support yourself (and your family) for at least 72 hrs and a week would be better.

What will aid stations be like?
Long lines, lots of unhappy people, lots of stress, no where near enough hands/supplies to help everyone.

Can you drink water coming out from a broken water pipe?
Yes - but should you? If the water system is compromised it is a risk unless you can filter it or treat it somehow. For the walk home I would avoid it. Once home I have access to filters, stoves and chemicals - assuming everything isn't part of the rubble.

Good questions to ponder.

-Eric