Also, when you enter combat with a gate, can you use weapons to boost your chance of success?

No. You must pass a Fight or Lore check, which is different from a combat check (which uses weapons), so no, just your fight or lore and any modifiers to those (like the "Fight" skill or certain allies)

I thought we were doing it wrong, so I had to ask. thanks for the answers.

gretcha73 said:

Technically, yes. However, it's moot since you can't enter combat with a gate.

Don't be confused by avec's sarcastic comment: you can't use things that affect combat or spell checks when closing a gate. Only bonuses to Lore or Fight checks will help.