Most rides have seperate entrances for wheel-chair bound guests, but some rides that load continuously (Haunted Mansion, Spaceship Earth ect.) those are more difficult because the don't stop.
Actually, this is not right. Most of the rides have mainstream entrances that ARE accessible for wheelchair users. A small portion of rides will require a wheelchair user to use an alternate entrance, but that is a minimum.
You might have more success on the DISability Board with this question, tons of experienced people over there. But none the less I'm sure you'll have a great time.
Definately hop on over to the disABILITIES board. Great info. Amongst others stickies with pictures of how entrance can be, lists of which rides have mainstream accessible entrances etc. etc.
No need to print info either, since recently they've been printing the accessibility info on regular park maps. Is that not enough or are you a bit uncertain? Go to guest services at any park and ask for the seperate booklets that tell you all about accessible WDW.
Am I right assuming you can walk the total of distances from boarding area into rides? If so; take advantage of it.

There are more regular carts/seats etc. than those that are fully wheelchair accessible. Basically if you can transfer yourself, it tends to be a shorter wait than for the one or two accessible vehicles per ride. Most rides will allow you to get the wheelchair as close as a few steps away from a vehicle, seat etc. And yes, it is OK to do this. Heck, it's very OK to do this.

If it's difficult for you to enter rides with a continous loading; talk to the CM's working the ride. At some rides they can stop the loading to make it easier. Nemo is such a ride. Also at Toy Story mania, they'll pull a vehicle off the regular 'loop', so you can board it at your own pace before they re-enter it into the normal 'loop'. Not all rides can do this, but you'ld be surprised at how many rides can be accomodating as best as can be.
You will be going during busy times and with a wheelchair that means some patience skills. Crowds can get in your way and somehow you seem to magically be "unseeable" as soon as you use a mobility aid.

It can take some extra time moving around crowds, voicing 'Excuse Me' to get through since you are wider than those smaller spaces that are easier to slip through when walking. If you are prepared for that, you should be OK.
WDW is a great place to do on wheels. To give you an idea; I'm a 24/7 wheelchair user, no walking involved. Overall WDW is a breeze to do as a wheelchair user and most of the times I'm going solo.
Also think about where you plan to get the wheelchair. If you want to rent at WDW, what if they run out before you rent one for that day. Can you manage or would that wreck the day? Can you manage the (sometimes very long) walk to and from the busstop after a day at the parks? Could you still do a foodcourt run at the resort after a long day? Most find renting offsite has more benefits. Not only is it cheaper, but the chairs are of a better quality AND you've still got the aid to use to and from the busstop and around the resort if you find you need it. Have fun!