i just came back from a very similar trip. see my trip report here:
http://www.disboards.com/showthread.php?t=1664501
i guess my advice would vary depending on what you want to see. sounds like you've done some research about the place already - which is good 'cause the place is huge!
so here is how i do things to cut costs. let me know if you have any questions:
1. car or wdw transportation and airport transfers? i always rent a car from alamo from MCO when i arrive and drop it off at the dolphin resort near Epcot and then take wdw transportation to where ever i am going the first morning. this cost me, just recently, $32 for the one night. compared to the alternatives (ie; towncar or mears shuttles), it's much cheaper and you have the flexibility to do what you need to do the first night (grocery stop, etc.). i used a combination of discount codes and coupons found on the mousesavers.com website and in posts on the transportation board on the dis.
i picked up a rental car at the dolphin resort the morning of the cruise and drove it myself to port canaveral and parked there. this worked our to be cheaper than the four of us taking the
disney cruise shuttle from wdw to the cruise ($70/person round trip). i don't know what you are paying for the shuttle from MCO to the cruise line. is it free?
but this might cut costs...just to rent a car the day you arrive and the morning leave for the cruise. i know some rental car companies have offices at port canaveral. alamo doesn't.
2. onsite vs. offsite? depending on what you want, i think. a kitchen? condo. kitchen not important? offsite hotel. standards? depends what you are comfortable with. i have stayed at a few offsite places and have stayed at a bunch of the disney resorts. i recently stayed at coronado springs for 9 nights and then at the regal sun resort for 2 nights after the cruise. and it depends where you want to go shopping. i went to the premium outlet malls (everything my fiance and i needed)...which is in the lake buena vista area and very close to downtown disney. i would recommend staying close to there. the regal sun is close as is the comfort inn lake buena vista. stayed at both. both are decent enough and cheap. i think the regal sun was $80/night and the comfort inn was $50/night. both have free shuttles to all the parks. comfort inn has continental breakfast. regal sun is walking distance to downtown disney.
offsite condo, you will pay for parking at the parks - i think $12/day.
3. shopping? from either the regal sun or comfort inn, a cab ride to the premium outlet malls will cost you at most $10. i don't think you want to go into orlando to shop. the city is not that great. there are a few places people like to go to...the florida mall is big and has some good stores, but definitely not discount oriented. there's the bellz outlet mall near univeral and the premiums which are, in my opinion, the best i've been to. depends what you like to buy i guess though.
let me know if this was good or you need more info.