What is the best preset to use in Premier 5.5 for converting TV commercials in HD for broadcast? Is it H.264 HDTV? Also, if I am editing using various files such as RED, DVCPRO and other HD files which initial project settings should I use? This is with the end use to be for broadcast HD TV commercials.
The project settings won't vary. The sequence settings should generally match your footage. Your export settings will be dictated by the needs of the station.
Your broadcaster will have a published spec and requirements sheet with all the info required for deliverables.
Broadcaster specs vary from one to the other.
As Jim said match your footage to your edit sequence.....to which I would add..the lowest common denominator ( rez) of your source footages.