Dropbox won’t sync files that you don’t have read permissions.
You’d better not merge an old Dropbox folder while installing/configuring Dropbox.
You’d better not store symbolic links in the Dropbox folder, because the symbolic links will be replaced by the real files/folders when synchronized to other computers.
It is not a good idea to put a Git repository into Dropbox. First, a Git repository usually contains lots of small files which downgrades the performance of Dropbox. Second, it is better to push a Git repository to GitHub, GitLab, etc.