Private keys? I don't have blockchain based voting anywhere in my foundation, nor I mention private keys in my proposal.

This foundation is based on a proven model - take a look at Linux foundation to get an idea on what kind of corporate members a technology foundation might attract.

Personal memberships are more of a way for individuals to feel supportive of the effort, it won't add much to the bottom line (majority of funds will come from corporate members, the first member being Steemit Inc.)

Why Steemit Inc. invests in the ecosystem? Because they have a product built on it and they want to see it grow. Same logic applies to any potential corporate sponsor - if we get them to build their product on Steem, they will want to support the ecosystem.

As for staff - I probably should not have to explain how recruitment usually works? You reach out to HR companies and post job ads and hire dedicated talent. Some of it might come from Steem community, but realistically most of it will be career professionals from outside Steem.

Hope that answers your questions.