For the issue of syncing drafts to the server, I don't know of any fix for that. It is an issue of Mail and GMail syncing at the same time as you are sending an email. It saves a copy to draft and gets put on the server even though you sent the message. This is a known issue and has been so for several years. I doubt seriously that gmneary13 actually fixed the problem. I believe it just hasn't reoccured yet or he disabled storing drafts on the server.
Mail does allow you to disable draft syncronisation. It is not storing draft messages on the server. Open Mail's preferences, select Accounts tab, select the account in question in the sidebar, and choose the Mailbox Behavior's tab. Uncheck store drafts on the server. This will discontinue having draft messages created when you don't actually save a draft.
The imap draft mailbox will be placed back under the gmail account in the sidebar and a local draft mailbox will be created for that account under the main mailboxes when needed. If you truly wish to start a message on one device and finish it on another, save the draft first, then select the draft and move or copy it to the imap draft folder. Then you will be able to access it on other devices via the same imap folder.
It would be nice if Apple would fix it, but they haven't. It's seems to be an issue on computers and not iOS devices. Everyone just need to send feedback to Apple's feedback site about this issue. Apparantly there hasn't been enough complaints about it for them to do anything about it yet.
BTW: This is not specific to gmail. This also occurs with iCloud accounts. Probably with any IMAP account.