I will focus only your question regarding Oktoberfest.

First of all you should start looking into hotels early since Oktoberfest is the busiest time in Munich with a lot of tourists. Prices start to go up real quickly. Second if you enjoy Oktoberfest or not depends on your personal taste. Do you like large festivals with a lot (I mean really a lot of people, of which a lot are at least tipsy), loud music and hearty meat heavy food? If yes you will have a great time. Is it enjoyable by your own? I would say yes since your will sit with strangers on a large table so that you do not stay alone. By the way you have a big chance to meet Americans, Australians, New Zealanders, etc. but probably not locals. If you don't like to meet people you do not know than Oktoberfest might not the right place for you or at least you will miss out a lot since you might not enjoy the atmosphere in the large tents.