I stripped and took my aluminum/carbon Bianchi into the shop last week for re-painting. It was difficult to remove the carbon seat post from the aluminum seat tube, but I eventually succeeded. The post has a lot of whitish gunk on it.

Question #1: Can I safely clean with any degreaser, or are some solvents damaging to carbon parts?

Question #2: When I (eventually) reassemble, should I lightly grease the post? Slippage has never been a problem. I don't want it to become so stuck/difficult to remove/adjust in the future.

I am aware of special pastes for carbon seat post (never seen/used 'em, though). My understanding is that they are designed to provide extra friction to the interface (to avoid slippage)--which seems to be the opposite of what I need.

Naptha or mineral spirits will not harm carbon fiber parts. More agrressive solvents like lacquer thinner or acetone won't hurt the CF material, but could damage clear coats, so avoid those.

A light coating of grease won't hurt the seatpost, but if it causes slippage, then CF assembly paste would be necessary. The assembly paste is not an abrasive - it's more like a plastic gap filler.

If you ride in the wet, it's advisable to remove the post and dry out the seat tube, to avoid corrosion problems.

Pretty much any solvent will be ok structurally. As said above, the biggest worry is the finish, or if you aggressively scrub your frame with a wire brush.

DO NOT use grease. I'm not sure why (and dammit I should!), but the grease just aids it in sticking over the long term. I've seen more than one bike come in thats one piece frame/seatpost due to grease. Now that I think about it I think the white stuff is galvonic corrosion or something. Anyway, you can either struggle with a dry, sticky seatpost, try the paste or remove your seatpost often to prevent sticking. Good Luck!