Sorry you have to be here but welcome. Re AS, here is some info including guidelines from Johns Hopkins: http://urology.jhu.edu/prostate/advice1.php
Most of the guys on this forum are surgery patients, so you should get lots of good advice from them. There are not many AS guys and they don't post often but, hopefully, at least one of them will weigh in on this thread. From what you say, the good news is that you have all of the options and the bad news is that you have all of the options. It's a major decision that will probably affect the rest of your life so my advice is to take your time, read a lot (Walsh's book is an excellent primer), talk to all of the right docs and gather as much info as you can so you can make an informed decision. Then, should you choose treatment over AS, make sure you choose a doc who has experience, i.e. at least 250 procedures under his belt (there is definitive evidence of that, at least for surgery).
I do think it's a good idea to do the more extensive biopsy if you can. I didn't know about that option and doubt if it would have changed my treatment choice but nevertheless would have done it if I had known about it.
Finally, there are a few of us on this forum who have had brachytherapy (seeds). My experience with this is 6 months old and you can read my "journey" by clicking the link at the bottom of my signature below. I have been very pleased with this non-invasive choice. Another longer term poster whose hubby chose this procedure is JustJulie and she has a journey posted as well. Also JohnT recently had this - he is a regular poster with great insight who may chime in as well.
There is a ton more I could write but I'll leave it for now with what I have shared. You'll find everyone here most willing to share knowledge, opinions and support.