Check your airline’s web site to be sure, but here’s my 2 cents. 1) You can lock your bags. If the TSA feels the need to look inside (it isn’t likely), they can break the lock (or the bag). There are locks which the TSA can open with a TSA master key. Look for “TSA lock” on Amazon or where ever you want to shop. I think the plastic clasp is a great idea. Avoid putting valuables in checked luggage (carry them on) and just zip tie the bag closed. 2) Overweight policies are specific to airlines. Check their rules. Looking at the American Airlines site it looks like $100 if you go over 50 pounds. Best practice is to travel light. If you really have to take heavy stuff, consider just shipping it USPS/UPS/Fed Ex /whatever instead. 3) Carry-ons are a usually a problem only in that people carry on TOO MUCH junk and the airline doesn’t enforce the rules and there’s not enough space in the overhead bin. I typically carry a small backpack for the overhead and a shoulder bag to keep on the floor (the rule is it has to fit under the seat in front of you). Basically I carry on the essentials to live with in case my checked baggage gets lost (it never has). 4) I used to fly twenty times a year (post 9/11) and I have never been troubled by the TSA. Wear a minimum of metal (I have a belt with a plastic buckle for traveling and court houses). Put ALL your loose stuff (phone, keys, wallet, etc) in your carry on. It’s not a problem in the bag, on your person it sets off the alarm and they make you empty your pockets and go through again. Keep liquids in your carry-on under 3.4 ounces. TSA says – “You are allowed to bring a quart-sized bag of liquids, aerosols, gels, creams and pastes in your carry-on bag and through the checkpoint. These are limited to travel-sized containers that are 3.4 ounces (100 milliliters) or less per item.” I carry an empty water bottle through the scanners and fill it up from a drinking fountain in the waiting area. In short, try to minimize your baggage & carry-on, get to the airport a couple of hours before the flight, be friendly to the TSA like they’re your mailman or a store clerk. The worst you are likely to encounter is long lines.