They both have the same meaning. "I will try to be better" is correct and I recommend using this one. "l will try and be better" is not exactly "correct" but it is fairly common in informal speech. Don't use it in essays/written exams though. I hope that helps Jamie (www.italki.com/jamie.teacher)

To correct number 1 you need to do this. "I will try, and (x hopefully) be better." "I will try, to be better (and X overcome)". You need to add in the (X) verb/adjective or noun.