The DL tickets do expire, but its 14 days the first date of use, for the one you buy ahead of time.
They also have park hoppers, that will let you hop from DL to DCA. But I think that the hoppers have a 3 day min. But who know they could be running a special when you visit. And I could be wrong about the min days.
DL does have fastpass, but they just recently took the Haunted Mansion and POTC off the fass pass system, it just caused a big traffic jam in the area. So you can no longer get a Fastpass for those rides.
The DTD Disney area is nothing like the one at WDW, small and really not as much to do. But luckily it's free!
Tomorrowland is basicaly down right now, Space Mountain is still closed. All that is really there is Star Tours, and its just like the one at MGM. And the shops. They are still working on the New Buzz ride, they are hoping that it will be open for the 50th.
The Castle is now all covered up with scafuling (sp?) and being repainted to get it ready for it's 50th birthday. So if you are hopping to get some pics of the castle, they will just be of a big blue square.
Make sure you check out Disneyland.com to see what will be open during your visit and what will be closed.
But go and enjoy what you can! I know I will, in just a few weeks!
Make sure that you check out POTC, The Haunted Mansion, and the orginal Tiki Room. They have there difference from the ones at WDW. Try to have lunch at the Blue Byou, it's located next door to Club 33 and the POTC, in New Orleans Square.