His chair - can we presume it is a folding, manual chair? Have you been out around town with him yet?

Airlines need to be alerted ahead of time, but otherwise should be the easiest part. At the counter make sure they know it is his chair and they'll ask about batterry. If it is manual, the obvous answer is "none".

At TSA, they'll ask if he can walk. If there is any question about walking through the magnetometer, just say "no" and they'll do a pat down while he stays in the chair. Leave some extra time - you'll usually be sent to the side and they'll call "male assist" to get someone to send him the bypass route. They may ask if you want a private screening area, but that probably is best declined. At the gate, say hello to the agent - who should be expecting you - and they'll ask if you want an "aisle chair" to pre-board with. This is the narrow chair that can roll up the aisle to get you to your seat. Staff may be more or less familar with all the straps and things. Your chair should get a "gate check" or "deliver at aircraft" tag and you should get a claim check for it. On the far end, they'll usually advise you to remain seated until everyone else is off and then will be very helpful. Don't book any tight connections!

Lavatory on board? Several options, but unless it is a 777, not easy. Have a plan ahead of time!

Good questions on the transfer from airport to hotel. You can request - in advance - an airport shuttle operator to provide an "ADA van" that would have a lift and he could stay in the chair. Hotel vans are usually awkward to transfer to seats. A normal cab or rental car MIGHT be easier. Here in San Diego, you can actually get a wheelchair ramp cab at the airport most of the time. Any of these options can have problems - even with pre-booking.

Have a cell phone with all of the numbers you've used loaded in it.

Most hotels will have "accessible rooms" but that covers a lot of ground. Desk staff are often amazingly ignorant about where they are. Another area you may have problems. I would call the actual hotel ahead of time to re-confirm. The "roll-in shower" option may be best, but that can mean several arrangemnts. Best is probably the fold-down bench that the wheelchair stays outside the curtain and you can slide over. Will you travel with a transfer board or rely on the grab rails?

Other rooms will have a plastic bath bench. These can be flimsy and need tightening of the screws - be careful! Call the desk if things aren't right. Some will lack anything. You can expect the adjustable shower knob to be left up high.

Talk this over with his PT/OT staff. They often have a practice setup available to make sure all of these steps can be done reasonably.