Even though you are unlikely to get late check-out, you can stay at the resort until later -- use the pools, etc. -- and be able to clean up and change clothes prior to heading to the airport.

Re: coffee maker... IIRC, it was a programmable model, pretty standard, but not an espresso maker for example. Were you looking for something specific?

Re: which building... Your preference will mainly depend on what you plan to do *at* the resort itself -- which pool, for example, and if you mind walking a block or two to get there. They have carts within the resort if walking will be a difficulty. And shuttles to other areas around the resort. Don't expect an ocean view, because it is well inland. A golf course view is more likely.

Other... The pools were great. Really enjoyed the various settings.
There are numerous gas grills & picnic tables throughout the resort.
Sometimes we walked over to HWV itself, to be able to view the ocean and swim in the lagoon. Sometimes we drove over there (we had a car, but not required). We also walked (and drove) to King's & Queen's Shops for more dining & shopping variety. Those things are each a mile+ away, but we were on vacation so not pressed for time! (we chose to walk & drive vs. shuttle so that we could leave when we wanted, rather than wait a few minutes for the shuttle)
We walked the petroglyphs trail in the area. Also hiked the ancient trail -- both ways -- from Waikoloa resort area. You can go for miles, across barren lava landscape but also through other resorts.

To get a feel for the layout of the area, check the following sites for maps and other information:
waikoloabeachresort.com
hiltonwaikoloavillage.com