No, there usually is not a comma after LLC. However, it will depend on the business and how the company was registered.
No, a comma does not go before the word 'in'.
An comma goes before so
It could go either ways?
before
No No
Example: When I went to my friend's door it was locked; however, I knew where the key was. OR When I went to my friend's door it was locked, however, I knew where the key was.
After
no
after
after
No.