[NiteWave]

Can someone post a guide about How to correctly enable cagefs without suexec?

the answer is at #9 reply in this thread.

If I enable cagefs without suexec, all the files become unwriteable, because litespeed run with user nobody.

this is just the purpose of "cagefs without suexec" mode, it's just what some host need. please refer #7 reply in this thread for more detail.

can I keep suexec enabled?

yes. there are 4 choices when set
lsws admin console->Server->General->Cloud Linux:
Disabled
LVE
CageFS
CageFS without suEXEC

generally in shared hosting environment, you should always enable php suExec.
and with this special combination:
LSWS 4.2 with PHP suEXEC daemon mode
+ CageFS without suEXEC

you can have php running as noboby for a user who enabled cageFS.