This should only happen on the first sync with a computer. Once you click Trust, the next time you plug in the iPhone to that computer it shouldn't ask again. If it keeps popping up it maybe a bug in iOS 10 that's effecting a small group or it may just be residual garbage files from a previous backup and a wipe/restore can fix. I'd wait to see if it continues in iOS 10.1
This should only happen on the first sync with a computer. Once you click Trust, the next time you plug in the iPhone to that computer it shouldn't ask again. If it keeps popping up it maybe a bug in iOS 10 that's effecting a small group or it may just be residual garbage files from a previous backup and a wipe/restore can fix. I'd wait to see if it continues in iOS 10.1
Unlock the phone to the home screen, plug into Mac & Sync. Keep phone on the home screen until iPhoto opens on the Mac to transfer the photos. The unlock during the transfer is clearing the Trust message and taking you straight to home.
I never use iCloud on my mac, why would I ever want to? I travel a lot and often have no internet, so don't want to rely on any cloud based system, it has to work standalone or nothing for me.