https login questions

Hi,

We are running wp multisite instance on let say blogs.domain.com, so the user blogs are something.blogs.domain.com or something.something.blogs.domain.com. I wish (not done yet) all users to login (just login, i.e. user/pass) only via https, but most of the user domains are not certified except the main site blogs.domain.com (or similar let say login.blogs.domain.com).

So far I could not find any solution, just a nice clue here:

https://make.ww.wp.xz.cn/support/user-manual/web-publishing/https-for-wordpress/

but the info looks quite outdated and short.

So, here are my questions:

1. Is it a good idea to force the whole network sites (….blogs.domain.com) to login via only one single wp-login.php URL?

2. Can I pass the Username and Password from the loginform to external https url and after that to return to the normal http wp-admin page.

If 1 AND 2 are acceptable and doable then could you navigate me trough the solution?

If not then what is the best practice to make https logins for all of my users that a maintaining non x.509 certified domains?

Best regards,
Atanas