AlwaysOn problems

Hello,

Cold you please help, can't find information in documents. 

I am implementing  AlwaysOn async on sql server 2017 enterprise. Initial data synchronization is full db and log backup.

its a non_domain and without Windows server failover clustering, I implement it via certificates.

So, the questions are:

1. how can I change backup time (I think I saw somewhere default is 15 min)?
2. where are kept the transaction log backups? 
3. when I am testing it, want to see can I bring secondary read-write mode(must do manually), database become "not synchronizing" and no action can be done there. How can I change roles of primary and secondary servers and how I can bring primary server to life after. 

Please help me ....