http and https

I want to buy a domain which were the juice and trustflow etc were build on https instead of http. I tried to get one but the guy doesnt understand when i tell him to run his expired http domains with his metric tools in the https to check. Is it a good way? Is trustflow and DA can be build on...

The default setting in Tumblrs as you all know, is "https". The question is... When we re-register an expired Tumblr with good stats (PA/TF/RD) on "http" is it good or bad to change it to "https"?

Hello guys, i am confused a little bit about http and https, I recently changed my website from http to https. so in WMT, my backlinks don't shows in https:// only in http:// version. 1- is that normal ? 2- should i build links to http or to https ? Thanks fro your replies and suggestions.