We settled on DavorOcelic, JustinLeitgeb, and MichaelOlson as the new team of system administrators, along with AdamChlipala transitioning to only the role of author and maintainer of custom administration software, but no day-to-day support request handling. The new team will lead the planning of our new hosting infrastructure, but we'll keep our current admin team until that's ready.
We chose Hurricane Electric as our next colo provider, pending any new information that might come up. You can find the quotes given to use by them and other providers on ColocationProvidersEvaluation.
We decided that our new hosting plans require purchasing the following hardware: one server that all members are allowed to log into, one server accessible only to admins, a network-accessible serial console, and a switch. More detail on Hardware.