3. CTC say there is now no guarantee of a UK base, only that its more than likely you will get offered one.
CTC flexi crew are never based out of the UK (due to the their cadet structure). So if you train with CTC the only time they'd base you abroad would be if you got a perm straight ahead and they asked if you wanted LIS / OPO.
Only Parc cadets get sent to Germany. (No flexi in France / Italy / Ams).
Regarding failing interviews, the Luton interviews has been there for many years but they did downgrade it at some point to BC chats. Don't be afraid of these interviews as 99% pass. There are some who don't but these select few were ones who really don't fit the company ethos.
Hope that helps.