Sorry for the delay
to answer your questions:
1, outlook for mac 15.8.
2. no also working in parallel it didn´t work
3. iCloud and exchange
4. I am running 3 exchange acconts and one iCloud account. two of the accounts are only for contacts and calendar, those sync, also the icloud accounts sync. Only the exchange accounts with email docent sync after one or two minutes..
best
Gerhard