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First challenge is to know that only one person will be able to work on the shared workbook at a time. You will find websites on Excel that explain more than one person can access an Excel Workbook at the same time BUT
inevitably there will be errors and data lost. So, one person at a time is the norm.

When you say lock out access to some areas for selected employees ... that is very doable as well. It is easier to lock out one or more sheets that are password protected rather than locking out a few cells or rows on a single sheet.
The latter is doable but requires more thought and coding (at least in my view).

Tracking who changes what, when, etc. is also very doable. I have several small examples that will work nicely for your project.

Does this help ?