Storage Question: my PC, Tablet and smartphone are all connected... all via my Google account

[wyn borkins]

5. Physical Drive Storage On Your Tablet Versus Google Drive (Cloud) Storage

Not sure I understand your question(s); however, if you share one Google Drive storage account among your three devices, then:

(1) Google Drive storage offers 15 GB for FREE

(2) If you require more Google Drive account storage, then switch to a 'paid' Google Drive account as detailed here.

(3) Get 100 GB (of Google Drive storage) for about $2.00 per month

(4) Get 200 GB (of Google Drive storage) for about $3.00 per month

(5) Get 2 Terabytes (of Google Drive storage) for about $10.00 per month

Google Drive storage is 'cloud-storage' wherein the 16 GB storage on your tablet is (most-likely) physical storage WITHIN that device and has zero impact on your other devices and zero impact on your Google Drive (storage) account as well.