First, congrats getting your next gig and i would pick up as MUCH tips as you can, observe the main tog and just pick up little things. For example, I've seen a tog where when they are (yup, a couple who shoot together) at the bride's mother's house getting ready and they would look around the house at the family photos on the wall, see a photo her parents has on THEIR wedding day and do an homage to that. It is not necessary, but it's a nice touch if you can pull it off.
No harm also asking your local tog to be his second but i wouldn't think he would let anyone follow him knowing you'll be competing against him lol For one thing, he would have to protect his sales, another person shooting means he might lose prints sales, and also if you 2 don't get alone then you'll be more a nuisance to him than help, not saying that you are!
And as for wedding in December...get yourself some FAST glass, the sun starts setting by 3pm in December !