+1

1. Paste for sure.
2. Torque wrench. The clamp may have the proper torque printed/engraved/cast/machined on it near the bolt.

Basically you want it as loose as possible without allowing the seatpost to move. The paste is like traction goop, it really firms up the connection.

I'd say:
1. Go to your shop. Buy a tube of the paste.
2. Either buy a Ritchey or similar pre-set torque key. It clicks automatically when you're at whatever torque the key is set for. If your clamp requires some other torque then you should buy the torque wrench set.
3. If you ask the shop to tighten your clamp, definitely buy the paste from them. Just like you don't want to eff up your carbon frame, they need to sell stuff to stay in business so you can walk in and ask them for a favor so you don't eff up your frame. The only time a person can be a "SUPERTool" in a shop is if they ask for something for free/favor and don't buy anything in return.