I am deciding where to store tds file for sharing among users.
The location I am thinking of using is a read-only web server space.
This way, no one can overwrite our group's tds file unless we all agree on the changes and save it
on a 'development' server first then roll it into the 'production' server space.
Any thoughts on that method?
It sounds like you don't have Tableau Server in play here - correct? If you did, you'd want to use Tableau Server's "Data Server" component to do this for you.
Dev shops will sometimes use their source management system to host the tds to take advantage of check-in/check-out.
A R/O folder on a file system or web server could also work, however!