Has anyone somewhat recently transferred from T1 to T2?

I should have plenty of time (~4 hours) to make it work, just wondering how well/bad the process is and if it might make sense to just enter the country and take the monorail.

2 additional questions on CAI:
- Does BA usually issue mobile boarding passes ex CAI?
- Does the monorail run through the night or does it stop for some hours?

Thanks in advance