Do I…
- selection synchronisation - every minute or automatic?
- Select the checkbox on Quit or Deactivation?
- Select Duplicate Documents in the event of a conflict?
These are all questions YOU must answer. There isn’t a mandated behavior or we wouldn’t have presented the various options. 
Silly question, will the sync be faster if I connected the ipad to the Mac?
Do you mean a hardwired connection of the iPad to the Mac via Lightning cable?
Yes. Or USB C cable for the iPad Pro. Just wondering.
If you disabled WiFi and only synced via the cable, I can’t say it would necessarily be faster but it would be a more stable connection. However, in normal use this phenomenon would likely only be useful in the initial upload or download of a database. Subsequent smaller syncs would probably not make much difference unless you’re adding large files.
You shouldn’t have Bonjour enabled in the mobile device is you have it enabled for the Mac.
And you should also check DEVONthink’s Window > Log for warnings.
Okay, will do. Thank you for the feedback. Can i ask shld i turn on the iCloud - either options while on Bonjour or should I just keep 1 only.
DEVONthink supports having a Bonjour sync and a remote sync option running. However…
- Do you really need a remote sync option?
- iCloud has not been very reliable for many people - including those not running DEVONthink. I’d read my previous comment again and carefully consider your options.
Thank you for your guidance in this. I will take it. By the way, can i ask, can I use Bonjour to sync on my iPhone the way I synced with my iPad ?
Yes