go bras basah complex and get those massive rolls of bubble wrap. go to some guitar shop, brudder the staff and ask them if they can give you one of those boxes that they ship the guitars in.
Yes, loosen strings, truss rod, so on and so forth.
Check-in wise, nope no problems as yet. Normal hardcase, no extra padding. I usually just make the ppl at the check-in counters put more than enough fragile stickers. Don't know about other airlines, but SQ doesn't run odd shaped / fragile items onto the belts (not guitar cases anyway).
They roll it away in a cage with other fragile items and upon arrival ground staff usually wait for you to come and pick it up at baggage claims (or atleast such has been my experience).