1. Most fun resort/pool/things to do for 2 and 5 years old boys
Depends on personality but I would suggest WL or FW if they are into the outdoors in any way. WL is a boat ride away from FW (the walking trail between them is closed for construction of Reflections) and sometimes a bus. FW has many activities (some free and most paid) that are mostly outdoors (such as archery, campfire with chip and dale, horse back riding, bike rentals, etc). WL does have a few scavenger hunts, boat rentals (bike rentals aren't operating because the trail to FW is closed).
2. direct bus to resort ( for afternoon breaks)
There are a few resorts that have direct buses with a single stop (AKL, Pop and AoA for instance). POFQ and POR will share buses during the down times. CBR, CSR, OKW, SSR have direct buses but have multiple internal stops. There are reports the All Stars will occasionally share among each other, but if they don't it is a single stop. I would look at which parks you think you would be spending at mostly and choosing a resort highly based on that rather than direct buses. While most of the Deluxes (BC, BW, WL, GF, etc) share with other Deluxes nearby you will find them to be closer to parks so the travel time even sharing can be less.
3. good/lots of food options
This really depends on eating preferences. Values mostly have food courts that are very American in nature and lack any sort of table service. Moderates and Deluxes food choices are generally themed heavily to that resort's theme. CSR is mostly Spanish/Latin American in nature, CBR is Caribbean, WL/FW is very rustic American, etc. Deluxe offer more TS and QS whereas Moderates are a happy medium between value and deluxe. I'd have to count it up but GF might have the most "food options" under one resort but 3 are signature restaurants.
I will say the MK monorail resorts probably offer the most out of park food option because you have a total of 3 resorts a short monorail ride away. WL/FW is also accessible direct from MK or CR via boat which is about 10 mins travel with up to 15-20 mins waiting for a boat.
A common critique I have heard for BC/YC and BW is that there is very limited QS options for food at those resorts. But Epcot is a short walk away as is the Swan and Dolphin which have great options.
4. not much walking involved to the food courts/lobby etc.
Deluxe (aside from SSR, OKW, AKL-Kidani) are all fairly easy to walk to the lobby, mostly indoors (besides GF, Poly off the top of my head). Moderates (aside from POFQ) are fairly spread out and generally require a larger walk. The values are all outdoor walkways (like moderates too) however generally are more dense than moderates.
5. fun/heated pools, splash etc.
All pools on property are heated as far as I know. The ones with notable splash pads are WL, GF, AK, and AoA. Deluxe also offers zero-entry generally.
6. more centrally located ( without being super expensive)
Again this depends on the parks you want to visit. But the most centrally located for all of WDW are probably the Epcot/HS/DS resorts (so BC/YC, BW, CBR, Swan and Dolphin, POR/POFQ, SSR and OKW).