It's only a 1 hour drive there for us. Consequently, we've been there a "few times". Going again in May.
Yes, it will be hot. Dress appropriately, stay hydrated, use suntan lotion. You'll be fine, just like the other million people in the park who take these simple precautions.
Fort Wilderness is a very nice place to stay. Your Jeep will be great for driving off the resort into Orlando if you so desire. You won't need it for going anywhere Disney related. I copied the following from their website, and keep a copy on my phone. Makes travel easy.
Fort Wilderness Transportation
In keeping with the wilderness theme, motorized vehicle transportation within the grounds is prohibited unless entering or leaving the resort. Alternatives are bicycles, golf carts, the internal bus system or walking. Supply is limited, but golf carts can be reserved up to one year in advance by calling the Cart Reservations at (407) 824-2742. The two internal buses are called Chip and Dale. The external bus routes are the Crockett and Boone.
To get to:
Magic Kingdom - take an internal bus to the marina and take the Magic Kingdom boat
Epcot - take an internal bus to the Outpost bus depot, and take the bus to Epcot.
Disney Hollywood Studios - take an internal bus to the Outpost bus depot, and take the bus to Disney's Hollywood Studios.
Disney's Animal Kingdom/Disney's Blizzard Beach Water Park - take an internal bus to the Outpost bus depot and take the Disney's Animal Kingdom/Disney's Blizzard Beach bus.
The Hoop-Dee-Doo Musical Revue is a dinner/show within Fort Wilderness. Fun for the family, but if you've been to it once or twice, the show doesn't change. Make reservations early for this too.
Hope you have a wonderful trip!