You have a lot to think about and not a lot of time to decide. If you are going to buy a resale contract, it could take up to 4 months to actually get the points from the date of your initial offer. If you are buying direct, you'll have the points within a couple days, I think. You need to do some research on all your options. Based on what you posted, if I were you, I'd probably buy a large VGC contract that I knew I would keep using and book a bungalow at 7 months since people always say it's easy to get those at 7 months. It sounds like a large VGC contract would be easy for you to keep using for a few years or longer. Of course, it will sell immediately if you decide to sell later.
My own thoughts on your choices (if it was me, since I obviously don't know your habits and travel patterns):
1.) Rent from Disney and be done with it? - If I were only going once, heck yeah, I would do that because I like easy stuff. I like being able to cancel on short notice and not having to stress out about trying to get a reservation or more points, etc. If I were going to use more than once, I'd start thinking about other options.
2.) Rent from an owner or a broker? - Not my first choice because all the money could be lost if we had to cancel. I've had to cancel vacations at the last minute for health issues a couple times before. Even with trip insurance and getting my money back, it sucks. If I couldn't get my money back, that would suck all the more. However, if you are confident that you won't cancel and that even if some of the people had to cancel, some of the people would still use it, it may be a good way to go. Make sure you understand the cancellation policy and find trip insurance that will cover a timeshare rental.
3.) Buy a contract for this? - Yes if you are going to use it again. You are looking at a large contract which is harder to resell. You can buy Polynesian to make sure you get what you want and if you buy direct, you can book 11 months in advance and feel very secure about it. If you buy resale, you'll be able to book at 7 months, but you may not have your points available right at 7 months and it may be more difficult to book exactly what you want. If you decide you want to visit WDW every couple years, it could help you with that. As you already know, you can rent your points or resell your contract, but a large contract will be more difficult to sell. If you are buying direct, you can buy several smaller contracts, which will be easier to sell, but you may have more closing fees. If you do several smaller contracts, you can always keep one and sell the rest.
Buy a large VGC resale? - If you are serious about staying at DL on a regular basis, just do this. If you don't have enough points to book the bungalow, you can have points transferred in by another member for whatever they are charging to rent points, but if they are transferred in to your own account, those belong to you and if you need to cancel, you still have those points to book somewhere else.
Lots of things to consider, but it sounds like money isn't one of them. So, that helps a lot. How much time and effort do you want to put into this? If you don't mind spending a lot of time going through the buying process, transfer process, selling process, etc., that sounds like a good plan. If you prefer to be one and done, it will be much easier to rent the room from Disney if they rent those to the public. There's a broker that rents points about $24./point that will give you cancellation protection. I don't think you get your money back but they give you a window of time (maybe 2 years) to rebook.