Yes, the summit will have a deck for walkers/joggers. It is located on the Sunrise deck 11 (above the pool). This is the same layout as the Infinity, of which I was on in March. Hope this answers your question.
No. And this is true of all Millennium class ships.
The Millennium class ships do not wrap around. Not only do they not wrap around the front of the ships, like all Celebrity ships, they do not even wrap around the aft of the ships the way the older Celebrity ships did. Also promenade deck is not teak.