Yes, They've shown videos of how to pair them (Exactly the same as you would on Switch 1) on the App they put out.
You can still use the Pro1 Controller and "Old" Joycons on the Switch2.
I've never noticed any ads so it does it job for me. As for Collabora Office, It is to my knowledge - https://github.com/CollaboraOnline/online (It's also used for the iOS/Android apps).
On iPhone/iOS you can download content blockers to have adblocking on it(Limited to Safari only); Personally I use Adguard Pro.
I think I've seen some people use a VPN/DNS to have systemwide blocking but I've not looked into that personally as my router supports it.
I use Collabora Office as my Office Suite, again on iOS; LibreOffice on my computers.
To try sell you more shit