1. iOS is not designed to backup to Time Capsule. Apple designed it to backup to iTunes in a computer or to iCloud.
See How to back up your devices using iCloud or iTunes - Apple Support
2. Any data on the computer including iTunes and photos will be backed up by Time Machine at one hour intervals.
3. Remote access to TC for backup is a bad idea.. Apple used to have active discouragement of the idea.. now they simply say nothing but I think you will find TM will simply not work to remote TC. It is much more likely to break the existing backup.
TM can backup to multiple targets.. get a 2TB USB portable drive and plug that into the laptop when you travel. Or use iCloud -- Cloud storage of some nature .. photos by default can be setup to backup to iCloud just like iOS.. and that will work a lot better remotely.