Hi Uijoong-Kim,
I will not answer all your questions but only the part on:
This is kind of related to this topic : Sonar integration with Bitbucket (GIT) - #2 by Carine_Bayon
And the answer is now “Yes, we support PR decoration in BB”!
See the announcement of BitBucket PR Decoration and official release thread here.
As you can see, you will need to upgrade to SonarQube 7.7 to benefit from this amazing new feature 
Enjoy it !
Carine