Which airport.. that can be influenced by your location and pricing.
Basically SNA is a cab ride away.. LAX requires a rental car or other type of shuttle. But if one is significantly cheaper.. it can make it worth it. LAX you might be able to get a direct flight.. SNA will likely be a connection, etc. You need to simply balance what you are willing to tolerate in travel vs the pricing that is available to you.
Travel to DLR and costs are always about balancing where you will spend. There is no 'one way' to do it.. each generally has trade-offs.
Example: you can rent a car.. but most of the hotels have parking fees. You can find a hotel that doesn't have parking fees, but it may be more expensive or further away.
You can avoid renting a car, but your hotel choices will be limited by distance. There is a bus that goes around the resort area to all the hotels (the ART system) which you can pay a few bucks for. Proximity to ART may be a selection criteria for hotels.
Here's my decision tree..
I don't want to pay to park at Disney.. so I won't be driving to the parks
I don't plan on visiting other areas on my trip.. so I don't really have a need for a car for daily things..
Since I won't be driving around, the car will just be sitting there, and I don't want to pay for a car just to sit there.
So I picked to fly into SNA so I could just take a cab from the airport to my hotel. Flight prices were the same for me because I was flying on miles.
For hotels,
You can try to pick hotels that are
0) disney hotels
1) right across from disney
2) within walking distance
3) on/near ART buses
4) in area, and you expect to drive
The pricing as you would expect.. basically starts higher and works its way down. The Disney hotels are basically WDW deluxe pricing (slightly below that.. like a Wilderness Lodge type pricing). The hotels across the street are more modest hotels, but charge a premium for their location (~100 to ~150/night). These are basically upgraded motels.. but not bad. Just don't expect a Hilton.. think more.. La quinta
As for when to go.. this thread does a good job of kind of outlining things to be aware of that impact crowds
http://micechat.com/forums/disneyland-resort/162619-when-will-busy-disneyland-2012-edition.html
For less than $10, you can also buy into touringplans.com for more detailed info. But basically it's the things you would expect.. holidays, school breaks, disney events.. followed by more localized things like passholder blockout boundaries, conventions in town, and 3rd party events (like Gay Days). Seasonally, it's SoCal.. so unless you want to be on the beaches, much of the year is interchangable.
What people often steer trips around is Disney's seasonal offerings.. like Holloween and Christmas... which also significantly impact crowds.
But for instance, we are going Jan1 through the 5th. This is after christmas and new years.. but the christmas decorations and events are still going on. We are also going during the week, not the weekend. Hopefully this will lead to a reasonable crowd level.. and we still get to see Christmas in DL.
Hope that helps..