excel file sharing with multiple user access and revision controls

hello,
i am looking for a solution configuration which will allow multiple authorized users to access an excel workbook to update content/information.
parameters would be:
-users are all remotely accessing the spreadsheet. (currently approx 5 users need access to the files)
-need some level of revision controls where users to avoid data conflicts
-existing spreadsheets have multiple links to other spreadsheets
-existing spreadsheets have embedded macros to automate input
-ideally if we can track who has made changes or is using the file it would be helpful
-ideally if concurrent access is available and can manage updates it would increase our efficiency rather than only one users updating at a time

right now we are using a local server with 3 Remote desktop cals; however, we wanted to move this to a hosted solution with automatic backups

any guidance would be greatly appreciated.
i would be willing to retain someone to help implement the solution if available.

thank you again
Mike