I have a unique idea where I want one user (not master) to be able to create users/galleries/upload photos all in one page. This user required unique rights to only be able to see this new page. Before I go about hacking away I was wondering if any recommendations could be made as I am quite fresh to zenPhoto.

Zenphoto does not have that but probably you could do that using the object model. Best see the documentation. You could do it as a plugin that creates an admin overview utility then you don't need to hack anyhting. Some work for your to do.

I think one of the most pressing issues I'm having with this is checking if users are logged in or our. Might there be a tutorial on how this is achieved?

There is a function zp_loggedin() which will return the rights list of the logged-in user (of false if there is no logged-in user.) Beyond that there are object methods to check right to do something on the object. Look for isMyItem() in the documentation.