I've used Skyauction at least 10 times with great success. However, I've almost always used their "buy it now" options instead of bidding. I find this much less stressful and time consuming, and often the price will turn out to be just as low as bidding.
Most of the times I have bought the "Vacation Certificates" (which are now priced at $259 plus $20 booking fee). After buying these certificates, I've been able to book weekly stays at 2-bedroom condos at places like Summer Bay, Silver Lake, Vacation Village at Parkway, Wyndham Cypress Palms, Bryan's Spanish Cove, and Orbit One Vacation Villas. I'd say all of these are family friendly.
You pay for the certificate right away, and then you usually have at least 6 months or so to book the property of your choice at the Resort Vacation Certificates website (be sure to look at the site first to see if there are options that fit with your schedule).
Make sure to read all the fine print before purchasing with Skyauction. I think most everything is non-refundable and non-changeable, and once you've bought something from them, they don't care much about helping you if you have a problem. Customer service is almost non-existent. However, I still continue to buy from them because the low price is worth the risk. I've only had one minor issue out 10 bookings.
As far as shuttles go, most non-Disney properties will have infrequent and unreliable shuttle service, so it's difficult to depend on this method for getting to the parks. I always rent a car at the Orlando airport, and usually pay somewhere between $150 and $200 total cost for a weekly rental. You might consider this since you'll be saving so much money on lodging.
If you need to book something during high season (summer and holidays) the "vacation certificate" method may not work for you. Availability of these condos tends to be much greater in the off-season. If there is availability in high season, you may have to pay a hefty upgrade fee.
It's been a long time since I've done any actual bidding on Skyauction, but I'm pretty sure they will want you to pay for and book the property within a few days of winning. At the Skyauction site, click on "customer care" and then go to "terms." I think that will give you information you're looking for on payment policies.