As long as you don't forward external ports 80, 21, 443 and 3306 (HTTP,FTP, HTTPS, and MySQL), on your router or TimeCapsule to the local IP (on local network) of your Mac, those are not problems.
The XAMPP Security Concept is designed to prevent folks from accessing your webserver's critical components from outside your local network. You might need to edit the LocationMatch statement for a Mac network, as I don't recall if it includes the 10.xx.xx.xx Range that some Apple network components want to use.
If you only want to work on 'localhost', and you don't forward external ports to the machine you install it on, there are no significant security risks in running XAMPP.
As far as what XAMPP can do? once installed its a standard Apache Server, with PHP, Perl and MySQL - plus other goodies, like an FTP server.
Good Luck with your project.