According to Rania Sarras, owner of The Chimney Chap in Duxbury, Massachusetts, a certified chimney sweep should inspect and clean your chimney and fireplace on an annual basis.

You can repoint the bricks, but you must dig out the old mortar to a depth of 1/2-3/4 of an inch before putting in new mortar. You can't use any kind of a caulk, or at least you shouldn't.

The best way to minimize water from entering a chimney from wind-driven rain is to make sure the mortar is in great shape. You may have to repoint the chimney first.