Mixed Account Subscriptions

If I upgrade to Sales Pro, can I have other users in my company that still use a free plan to access my company data, i.e. in effect having mixed account subscriptiions?

Or, If I upgrade to Sales Pro, will all users in my company be upgraded to Sales Pro, and all future users will become Sales Pro subscribers?

How does the subscription system work, is it on a user basis, or on a company basis?

Yes, you can upgrade specific user to Sales Pro. You can mange your sales pro users under Settings > Manage HubSpot Sales Team