Do you mean the Quality Inn Plaza on I-drive?
Depending on where you are staying you can manage without a car, the transportation from the hotels to the parks is usually pretty good, however as we rent a car every-time we go I can highly recommend it - you just have that extra flexibility to travel around as you please, especially if you want to go slightly further afield - ultimately it just comes down to personal choice there.
The problem with 8 days is really you will struggle to fit all the theme parks in, Universal & Disney.
So the best bet is to visit the parks you really want to see, also if you spend everyday at the parks it will probably be a bit much so I would plan a couple of rest days for relaxing or maybe do some shopping etc
Universal parks have the advantage of being next to each other so you can simply walk from one to the other in a couple of minutes. Probably a couple of days would be enough for these, depending on if you plan on spending all day at the park when you go.
The general approach for many of us is to get to the parks just before opening at 9am, this way in theory the parks are quieter and the weather cooler (although conditions in October should be ideal)...it is common to take a break for lunch and then return again in the evening, should you wish to.
Once you have decided which parks and how many times you intend to visist them, I guess you can then look at the ticket options available.
The Halloween Horror Nights are excellent, to be fair though it is a long time since I have been to one - as for the meals question I honestly don't know as I have never tried this, sure someone will have done.
A good website that may give you an idea of what tickets are available and the prices is Maple Leaf who are based in Kissimmee, Florida - you could use their website as a guide as to what you can buy.
www.mapleleaftickets.com
As far as planning goes you can always just take it day by day when you get out there, must admit that is what we generally do.