Domain splicing

#1
Hello.

We have a clean domain without links site.ru and there is a domain with links site.com

If I glue them all links are transferred from site.com to site.ru?

If site.ru is blocked, can I glue site.com from it and glue it to the new domain, will the links be transferred to the new domain?

Do I understand correctly that you can safely buy links to the mirror of the site, and if the main site is blocked, then just glue it with the new one and the entire weight of the links will be transferred to it?
 
#3
And tell me more, I have a drop domain with links, I make a 301 redirect to one page of my site, do I need to move from the drop domain in the webmaster, or is it enough to simply register a redirect?