re: Reusable (and Gemini)
Maybe it's more important to keep it in space for a very long time than for it to be reusable.
Maybe one doesn't prevent the other, but might make it less interesting.
About the heat shield, well there are 2 kinds now known. Ablative material or the tiles.
I think Gemini 1 (unmanned) was re-used as Gemini 2 (again unmanned) to test the Gemini spacecrafts.
Raoul