It's the same meaning. The first is a little more formal though.

I disagree with Cici I understand them perfectly. However, "for as long as" and "as long as" have the same meaning. However, your confusion here is the use of the world "for". When should you use it and when you shouldn´t use it? Unfortunately prepositions in every language are hard and there are sometimes no rules. For example: We say "in school" but not "in home". Using the Phrase "as long as" or "for as long as" will require seeing a lot of examples. Sometimes they are interchangeable like the sentences you gave. Sometimes only one can work. For example: She had loved me for as long as I can remember She had loved me as long as I can remember. (Without using "for" his just sounds wrong.) This answer is as long as can be. This answer is for as long as can be. (Using "for" just sounds wrong here.)

Regret is not wrong. It means if you do something and are rejected for it, than it is a short pain. However if you do not try to do it, you may regret it for a long time, and have a lot of pain.

Adding "for" does not change the meaning. But I'm not sure what either sentence means. "Regret" is used incorrectly.