First off, don't forget to check out the thread here that answers all sorts of questions for WDW veterans heading to Disneyland. It's invaluable.
http://forums.wdwmagic.com/threads/guide-to-dlr-for-wdw-veterans.875596/
It is the rainiest month, but you have to remember that's subjective. For an East Coaster, if it rains it will seem like light showers or light to moderate rain. The upside to this is you'll get to watch the local TV stations absolutely lose their minds and go on
STORMWATCH! and have remote reporters breathlessly report that puddles have formed, a housewife in an SUV spun out on a freeway onramp, and some citizens have been reduced to using umbrellas. It's quite hysterical to watch, but locals don't know how ridiculous they look.
Average rainfall for February in Anaheim is 3.07 inches. As a point of reference, the average rainfall for Orlando in June is 8.74 inches. This past winter, thanks to the drought, Anaheim recorded 0.0 inches of rain; it was absolutely dry and rainless for the entire month. An El Nino is forming in the Pacific, so this winter could be rainy. But again, it's subjective.
Even if we get an El Nino, you might arrive during a dry week of sunny and 75 degrees, which can also be quite typical in February. Evenings will get chilly, down towards 50 degrees, so sweaters and light jackets are advised.
All that said, Disneyland has more outdoor attractions and dining patios that can close in rain. The Teacups, Gadget's Go Coaster, Goofy's Sky School, and Alice In Wonderland all close in steady rain.
I would expect some refurbishments. Previous marketing campaigns have never changed the routine refurbs in both Anaheim parks.
World of Color and Paint The Night will probably run nightly on weeknights this winter, as per the usual World of Color winter schedule. But Fantasmic! and the Forever fireworks will be Friday, Saturday, Sunday only. Make sure you've got one or two weekend nights to see those offerings. All other stage shows and entertainment runs daily that time of year.