Do I need to run a full node before the 2X fork?
Your coins are safe on Trezor, you don't need to run full node for coins unless you want to help mine.

If you want to access Segwit2X coin or any other BTC forked coins (in future) asap after the fork, then you should transfer your BTC coin to a lite client and get the private key of that wallet.

Or else, you can wait until Trezor supports Segwit2X coin, in that case, you will get those coins in Trezor itself.