Looks like you have lots of ideas now for tabling ... and even have your husband working on it already. If you need more ideas, as to what to do with the under area of your new cabinet, take a look at the many previous threads of how other quilters personalized that area for storage that works. One of the best to me are those that have nails on the ends to hang their quilting rulers.
Being that you like to sit up to your table, when pinning, you might want to consider enough overhang, so that the chair (and you!) can sit up to it, without your knees/legs getting in the way!!!
For a chair, a stool can work fine or look at adjustable drafting chairs. I have one for my sewing machine, as I found that the upper limit of a regular desk chair, was still a bit low (ergonomics come into play again!). The drafting chair lowest is about the same as the highest of a regular desk chair .... and then you can go higher! When I need a chair at my cutting table, it works perfect.