What are Gateway hours? Is this the time where a tunnel is up and running or the time where a gateway available?
Sorry but I am bit confused atm 
It’s when the gateway is provisioned and available to you.
So the clock starts when you provision and ends when you delete.
If you don’t want to have to delete and recreate the gateway, I think you can just change the password on the connection on the azure side (so the connection breaks), and when you’re ready to bring it back online, enter the correct password.
I don’t think this is able to be automated, but if you were working on a test environment periodically, I think this pauses charges since the connection isn’t up
I haven’t been in the cloud space for a long time but checking the pricing page it doesnt mention connections, only provisioned and available gateway, so i’m doubtful pausing the connection resource would pause the charges. Feel free to correct me but best to be on the safer side.
Pretty sure this isn’t correct.
You are correct. I wish there was a off switch for things live dev envs. So you can have it spun up and then shut it off on weekends.
I’ll have to go back and check, but I interpreted available to mean connected. I’m going to have some explaining to do if that is not the case 
Yea, I need to check and prepare an explanation for work lol
Terraform / Bicep / ARM templates
Delete on Friday, recreate on Monday
I have a feeling available means it’s not under maintenance or an outage. Which would make sense since it’s charged on hourly basis.
But yes, please do double check, hope everything goes well and you are not in trouble!
All of our is TF code. The issue with VPNG (using VWAN, not sure on standalone), particularly, is the IPs changes (public and BGP peering), so you need to update you on-prem infrastructure too.