I'm setting up a Community with the Napili template and having trouble finding documentation around setting dynamic/referential variables for page URLs. I'm also wondering if I'm thinking about this all wrong, since it should be pretty simple.
 
One of the first things I tried to do was add a menu item to the Navigation Menu - My Profile - that provides an alternate way for users to navigate to their profile. I added a Community Page menu item, selected User Profile as the Page, and have tried everything I could think of to replace :recordId parameter in the URL to dynamically reference the running user's User ID. What do I need to put here to get this to work?
 
I'll also need to set up Record Detail pages and navigation menu items called "My Contact" and "My Application" that reference the running user's related contact and active application records and expected to run into some challenges there, but I haven't even gotten that far. Any guidance would be appreciated!

I have performed a fast lookup and retrieved a list of objects. I need to make a decision based on the number of records returned - can I do this with a formula instead of having to use a loop to count the records?