"Judge Gordon Kolodny:
Well, this has been fascinating, gentlemen. Kind of like debate night at Mensa. Mr. Gellman, that TV spot you’re defending is emphatically vile. But, Mr. Shore, he’s right. Political speech is not subject to prior judicial review. And thank the Lord, or it’s all I’d ever do. (he slams his gavel) We’re adjourned."

If political speech were subject to judicial review, then I (as a judge) would spend all my time reviewing political speeches.

1. does it mean: "thank the lord, it's all I would ever do" ? -- Yes
2. can i say: "thank the Lord, it's all I will ever do "? -- No
3. and what's that "or" at the beginning of the sentence for? -- it replaces the 'if' semantically.
-- Are you going to keep playing that loud music all night?
-- No.
-- Thank goodness, or I'd go crazy! (= Thank goodness. If you kept playing that loud music all night, I would go crazy!)
-- Stop cursing or I'll slap you! (= If you don't stop cursing, I'll slap you!)
You'd better be good, or Santa Claus won't bring you any presents this Christmas.
(= If you aren't good, Santa Claus won't bring you any presents this Christmas.)