Help with Gmail

I recently bought a new MacBook Air and transferred contents from my old Mac to the new one. Problems with Gmail:

I have one Gmail account which seems to be fine. But the second one has uploaded emails from years ago but not the last 2 years. I can send emails from this account but do not receive any.

I want files and folders to remain on the Mac and sync to the cloud. At the moment there is nothing on the Mac unless I download it - so I can't work without an internet connection. I'm sure it is a simple setting but I have forgotten how to do it.

I also need help putting other email accounts onto the Mac and my phone. I used to use Mail but I'm leaving that and using Gmail directly.

Please quote for 1 hour's help. If we need longer we can arrange that.

I won't reply to AI generated blurb - all I need is a quick response saying yes, you can help and it will cost £xx for one hour,

THANKS! Dr James Thornhill