How often is peer-id changing? can it be customized, if I dont want unplanned tracker announces?

Is it what you are looking for:
http://s33.postimg.org/9c4188lwf/Setings.png

please try also   google - > site:tixati.com "peer id":  
Individual Tracker Options:  https://support.tixati.com/individual%20tracker%20options
Transfer Properties - Options -> Peer ID: https://support.tixati.com/transfer%20properties%20-%20options

default peer IDs reset every 36 hours maximum

you can figure this out if you watch a transfer's event log, it will show the peer id changes (or you can just manually watch your peer id in the properties)

if your IP changes or a transfer goes offline/online for whatever reason, the peer ID for that transfer will reset if it's been at least 6 hours since the last reset

none of this is adjustable, and there's no extra tracker announce

Peer-id change interval isn't adjustable however you can set custom peer-id that is static. It won't change between sessions.