On a prior stay, we added our friends to our reservation. They were staying off-site for a portion of their visit, and this allowed them ability to use pool, Disney magical express (DME) and stay with us for a portion of time. I made sure that they provided a credit card for their incidentals, and that went just fine. Since they were on our reservation. they were able to receive the magic bands. However, the magic bands were shipped to us in one box, and their magical express tags were also shipped to us. Since they're friends, it was easy for us to mail the DME papers with the magic bands box without our bands, of course.
This was their first visit, so it worked to their favor to have us "shepherd" them to some extent. They almost bought tickets to
DisneyLand to give you an example. Anyways, had we been on the dining plan, all persons on the reservation need to have the dining plan for the entirety of the stay. Luckily for us, our cost analysis revealed that we'd "lose money" on the various dining plans, so it wasn't a factor for our friends to consider.
Additionally, it didn't matter that they were staying with us for a portion of the time, they were listed on the reservation for the entire trip. Now, we weren't planning on swapping people in/out of the room, so I can't comment on the feasibility of that, which may be beyond your question anyway. I can't comment on having the same name on multiple resorts; our friends were off-site for a portion of time.
Lastly to pool hopping: Since you're staying at BWV, and when you add them onto your reservation, then they'll always have access to that pool. Also, you may have an option to use their pool, if there is no prohibition, such as for the Poly, BCV, etc. On our prior visit nearly all our friends were at Port Orleans, and we used our DVC privileges to pool hop there. Luckily, there wasn't a capacity issue and we were never checked. Had we been checked, it may have been okay since we had pool hopping privileges, but that privilege never guarantees access/use due to capacity for those guests paying for a Port Orleans stay.
Hope this is helpful, and you and your family have a wonderful time at Food and Wine!