I'll try to answer a few of your questions, and ignore the ones I can't answer...:icon_tong
How long until you make O-3 again? After selection for promotion by a board you will put O-3 back on after 30 months of being an O-2.
If you have been and enlisted or warrant officer for more than 4 years active service you will get the 'e' appended to your paygrade, but if you have been neither of these honorable things I don't know why you wouldn't just be an O-2.
Where you go is up to the Standardization Branch, but the last two folks at my unit who both had flown C-130s previously (one is and Air Force exchange pilot), went to a commercial outfit in Tampa called CAE for their transition course. You would come in as a copilot, but would quickly move through the quals to the left seat, first pilot and aircraft commander designations.
Don't know about deferring your transfer...sorry.
Haven't seen the boards lately, so can't answer your questions on when the next DCA board is.
Good luck.