I used to teach high school at a private school, and saw several kids come in and out of school in favor of homeschooling. Homeschooling, especially in the case of a child who has special needs (and yes, I believe that being gifted counts as a special need) could potentially be great for him/her. However, there are things that do need to be considered first. First of all, you have to be totally committed to it. I can't count the number of kids I have seen who are homeschooled, and the flexibility makes both them and their parents lazy - so they don't get the education that they could be getting. Second, make sure he has some sort of activity at least a couple of times a week where he socializes with kids his age. An awesome education will do no good if he doesn't develop the ability to get along and work out problems with others. Third, keep them on a strict schedule. I remember having a very bright student in my class once who had been homeschooled most of his life, and understood the material, but had a TERRIBLE time meeting deadlines because his mother had been flexible with them when he was at home. You don't want your child going to college without time management skills - that's a recipe for disaster.
Now, on to the other part of your question. I'm no expert on this, since DS7 is in public schools. But DD4 doesn't start kindergarten until the fall, and I do extra work after school and during breaks and weekends with DS7 to keep him challenged. So it's not exactly homeschooling, but it's close - especially during the summer. Anyway, at first I tried working with them together. That was a total failure. While I was explaining something to one, the other would need help, or one would be curious about what the other was doing, ....it was horribly distracting to both of them. So I put them on a schedule. They got up in the morning, ate breakfast, did their chores, then DS7 did his reading for the day while DD4 worked on reading, writing, and math. After she was done, I would give her a coloring book or some other quiet activity (we ended up getting her an art desk for her room, so she could occupy herself without distracting her brother) and work with DS7.
I also found that it was important to let them study things that they like. I was adamant that they would cover the basics - reading, writing, and math - and I also wanted them to work on some Geography, since so little is taught in school now. But when my daughter decided she wanted to be a vet, and my son went through phases where he loved astronomy and the presidents, I covered a little of that every day with them as well. It broke up the monotony and made them actually look forward to doing their lessons every day. It's a lot of extra work, but I think it's beneficial to them.
Hope this helped a bit!
