Oracle Database Discussions

Hello,
A checkpoint can occur in these situations:
- redo log switch
- after specfied interval
- time out
- by force

But, When checkpoint occurs will these things happens. Is these things correct according to my knowledge
---> Data Buffer to Datafiles (by DBWn) YES

---> Commit occurring? (redo log buffer to redo logs) NO

---> Log switch occurring? NO

---> Archiving rego logs? (By ARCn) NO

Soo, when checkpoint occurs only thing happens is writing dirty blocks from data-buffer to data-files.
It will Not happening commits/log witching/archiving due to checkpoint. Is it?

-----------------------------------
What are the occasions that commit can occurs?
Is it when the redo log buffer gets filled


What are the occasions that log switch can occurs?
after 3sec/ redo log file 1/3 full anyother?


Regards,