sonnyjane answered most of your questions. The hours in February tend to be on the shorter side, except perhaps around President's Day. On the week days the parks tend to open at 9 or 10 and then close anywhere from 8 to 10, depending. You can see the hours from Feburary 2013 here:
http://www.wdwinfo.com/disneyland/park-hours.cfm?month=2&year=2013
Christmas decorations usually start to come down the Monday after New Years. The last vestiges is usual It's a Small World Holiday which usually runs until mid-January. By February, unless something is overlooked, the only Christmas you'll find is the ornaments and other holiday decorations they sell year around in the stores.
As mentioned, you'll likely only have the chance to see fireworks, Fantasmic, and Mad T Party on Friday, Saturday, and Sunday. WoC should run nightly, unless it's undergoing refurb. That's another thing to point out; DL is currently experiencing a fairly high number of refurbs in advance of the 60th anniversary next year (2015). The 60th events are supposed to start in the "Spring", so it's possible that winter will see the last flurry of refurbs in advance of the anniversary events.
In terms of tickets; you can purchase them from Disneyland.com. Other have also reported having good luck with aRES, way.com, ebates/orbritz, and
AAA. Basically, stick to the reputable sellers and you should be okay.