Controlling XR18 via tablet vs PC in live gig



1. Is it better to control my XR18 during a live gig through a wifi-connected (via external router) Android tablet or through a wifi connected (also via external router) PC (laptop)? 

2. Relatedly, is there some sort of priority one gets over the other? For example, if one person is making changes through the PC does the PC somehow block any changes another person puts in through their tablet or phone (changes to in ear monitor AUX outs, for example)?

3. Finally, can someone confirm that snapshots are saved in the mixer whereas scenes are saved in the controlling device? If so, if I save a scene in my laptop and call it up at the start of the gig, can I then move my controlling to the tablet and use the tablet during the gig? Then at the end of the gig would I have to start the laptop back up to save the gig's "scene"?

Thanks and sorry for the complicated questions. I am new and we gig tomorrow.