There is always a strong debate when asking about staying on WDW property or off. I'm a Disney geek and actually follow some Disney Facebook groups and discounts get unpleasantly heated for some reason. I've stayed at both and like both.
The Fort is going to be expensive. I have a 1-week reservation starting next week and it's upwards of $1,000. There are no weekly or monthly discounts. It's a very campground-like setting with being fairly tree covered. Parking can be tricky as the roadways are fairly narrow and people are generally hard to be found if you need someone to move their vehicle.
Transportation is way more convenient - if you want, you won't have to move your vehicle the whole time you're there BUT it's often no quicker than driving. Most of the time, it requires 2-steps to get there: you take an internal bus either to the front of the campground (where the buses are for the Disney parks/destinations) or to the marina and boats. Lots of people use bikes or rent a golf cart to get around and skip that "internal" bus to save time. Depending on where your site is, walking may be an option for that first leg.
There are 2 pools. One has a slide and splash park for kids. It's fairly simply by Disney standards. There is a restaurant on site (expensive for what it is, but decent by Disney standards) and a couple of dinner shows.
TTO is a beautiful RV park. In general, it's fairly wide open without a whole lot of tree coverage. It can be difficult to get space in the winter and is fairly barren in the summer. If it matters to you- in the summer, the 50amp sites are generally sought after. You can usually find one, just maybe not exactly in the location that you want. TTO vs. the Fort are 2 wildly different feels/experiences.
Driving in, we found a "back way" through Flamingo Crossing that really helps cut out a lot of traffic. You'll need your car/truck to get around. In general, Disney isn't terrible with a dually (don't know your tow vehicle). Being offsite, you will be driving to everything. There are lots of restaurants on 192 and a Wawa (for their wonderful subs- not sarcasm).
It likely doesn't apply to you, but parking at Disney is free for annual passholders.