Don't wear uniform unless you want to be treated by custom agents thinking you are trying to do something funny, and you'll have looks from pax that isn't worth it. Once you step inside US border, do whatever you want, it may help with TSA.
About luggage, it's a rather country-by country standards. Some country would let you carry the tank on, some country would be very picky. At least when you go thru security overseas, they don't want your shoes off!
Tax wise, at LGW, it's about 110 last time i went thru, AMS was about 85, and i got lucky and didn't get charged by CDG. I think Europe wise, expect about 80-100 range for tax.
Be at the airport at least 3 hours early, so you have time to: 1) Stand in line for the ticket counter (not the check-in counter), 2) Explain to them what J/S means (Staff travel usually works pretty good), 3) They will collect your tax money, give you a receipt, issue you a gate pass to go thru custom, 4) Go thru security, 5) Wait at the gate for the crew to show up (Usually 1 hour prior to dept is their show time), 6) Explain to the gate agent what J/S means again, and 7) Try to sweet talk your way to a business class with the purser. 8) While serving meals, do not choose your meal unless offered first!! Most likely you will get your choice, but it's just a courtesy for paying customers to choose first.
There you have it, it's my little guide to overseas js.
