On point 1, Tatum is better than Brown. Both are really good. There are not that many I would trade Brown for and even fewer that I would trade Tatum for. In my view, unless Wembanyama or someone like that is offered, you trade Tatum to start the major rebuild, likely no less than 3-5 years of being bad and hoping you get lucky in the draft. It may come to that, but I am in no hurry.
Physicality? I am not that concerned. When the team is White, Brown, Tatum, plus a center and another guard, that group is plenty physical. When the center is Queta and the "other guard" is Hauser or Scheierman or Walsh, the problem is not physicality, it is how good they are. Queta and any of those guards are just not quite good enough. If Queta continues to improve, he might be fine as a starter moving forward.
And I don't think the team will be revamped. Tatum, Brown, White is a good core. Changes around the edges, sure, and if you can bring in Giannis, great. Maybe some other Brown trade. But all that is unlikely. Trades like that are hard.