What happens when someone sends me an iMessage/SMS during a restore? The restore process can take some time. What happens if someone sends me a message during this time that my phone is unusable? Will I be able to see the message at the end of the whole process? 

It's my understanding that when you restore your phone, your number will no longer be associated with iMessages until you reenable iMessages. What will happen if someone tries sending a text?

If I have the Messages set up with iMessages enabled on another device (e.g. MacBook), would I receive the messages there?
In my experience, when I send a user an iMessage while that user is unable to receive one, my iPhone (or whatever device as long as it is sending through my phone) will switch to SMS. When the message is sent as an SMS it will still arrive even after the recipient is re-connected. 

Note: I haven't looked through docs - this is just what I have come to through observation.