Syncing to someone else's laptop

Hi,

My friend has an IPad2 but has never updated it from the factory settings or software. The reason for this is because they don't have their own laptop and on the original Apple days you could only update your software whilst 'plugged' into a laptop etc.

My question is, if I plug their IPad into my MacBook to update their software - will it automatically delete all of their photos / apps etc? And replace with the content of my iTunes?

Or even worse, clog my iTunes with their items?

I'm thinking if they put everything on their ICloud and then restore from there?

Thoughts / experiences will be most welcome... Thanks!