Questions
 

Try - Team A attempts unsuccessfully, we have a PF 15 Facemask on B. Can B take the unsuccessful try and keep the distance on the suceeding spot.

Team A's ball 2nd and 10 @ midfield. A throws an interception @ the 40 yard line and B returns to the 20 yard line where he fumbles and A recovers again at the 20 yard line (30 yards behind the original LOS). Down and distance.

I think you mistyped in the PAT play. You said the FM was on B. B will not get the option, A will. Since the PAT was unsuccessful, A's option are to accept the penalty and replay the PAT or decline the penalty. Fouls can only be assessed on the subsequent kickoff if they occur during a scoring play. There was no score.

1st and 10 for Team A.

yes I did have a typo - thanks.

#2: 1-10 A at the A 20.

Canadian Ruling
 

2010 CANADIAN RULING:

A can move the repeated convert attempt from the B-5 to the B-1 or retry the convert from the B-5 and move the KO up 15 yards.

2010 CANADIAN RULING:

This is a double change of possession. Once B intercepted the ball (completed the catch), downs were broken and whomever was in possession of the ball at the end of the down, will have 1D/10. Result: Team A 1D/10 @ A-20.