What is best practice for synchronising 2 macs with a private 'cloud'?

Hopefully there are a couple of ‘Power Users’ lurking who can point me in the right direction…

Scenario: 2 macs (laptop and iMac), iPad, & Synology NAS running cloud station (but it could be the Drobo/Transporter equivalent)

Currently the laptop is the primary machine, the iMac will be a new addition. I am increasingly using the iPad in meetings now that I can access word/excel files etc. so easily but still need the power/flexibility of the laptop for some jobs. DSFile on the iPad gives access to all files in Synology Cloud Station if there is a good enough internet connection.

Some applications save files in ‘default’ locations (e.g. application support). If I want to be confident that I can access any file on either mac and have them synched what should be the root point of the sync?

Would the root of my home folder capture everything? Or would some important file locations be missed?

Are there any folders that should be excluded below the user home folder because they are used for system/application settings and could cause instability?

Are there any folders/files (outlook indexes?) that would be best left to only ‘resync’ on the work lan, or would be best excluded as they would keep themselves ‘in sync’?