Going to do a 3 Month Subscription and would like to know if I get a reminder that it will renew or if I have to mark it on my calendar, it’s been a while since I have done any Subscription other than WoW Token so I can’t recall if it’s an Auto Renew if it has an Email Reminder they send you.
Might not be a “Customer Support” strong topic but could not figure out where else I could ask this question.
Subscriptions are auto-renew by nature.
No, not emailed unless the payment attempt fails.
Once you have set up a subscription, going into your battle.net account page will show you the next billing date.
Perhaps for shorter sub periods, but I get a reminder email a month before my yearly renews. It may only be so for longer periods. Easier to forget something that happens only once a year. (Like my wedding anniversary. 
)
I actually got one last month I think and I just do month by month, not the longer ones.