I'm just your ambitious college student, decent guy and app developer that recently had a shock. I was best friends with a guy I knew from first to the third grade. I moved away and we lost touch. This was about...15 years ago I guess? Anyway he loved birds and one way he greeted me was saying Kolibri, hummingbird I think in German. Well in my other box on facebook I saw that word again from a attractive young woman. Long story short, my best guy friend from olden days was now a woman. Anyway she moved to my city and wanted to catch up with coffee or something and was really excited that I responded to her. However...I'm a tolerant, respectful guy but I don't have any real experience with this. I wasn't appalled, just shocked. I heard how the medical changes happen on some tv show or something a long time ago.

My issue is I certainly do not mind reconnecting with old friends and we were so close, but I still have the image of how "he" was, or rather how she "used" to be. My best mate, my partner from childhood I'm sure many of you can understand. Is there anything I shouldn't say or mention or should say and mention?

I would say not to over think the situation. Meet up and see where the conversation goes. Just remember SHE is a WOMAN and never was a male. Remember mutual respect and treat HER how SHE is today. Open doors for her, etc. Watch what you say about her past and let her bring it up and feed off of whatever direction it goes. If you over think and worry you are more likely to get into an awkward situation. Treat her normally and I think you will be just fine baby. Good luck! 

Do your best to not mess her name up, mind your own business about what's in her pants.  Those are the obvious faux pas.

Otherwise she's the same person.  Older, wiser, and most likely much happier.  Enjoy catching up.

Update:

things went just fine. It was somewhat awkward for me when she made clear she always had feelings for me and still does to this day, other than that we rekindled our friendship and talk about every other day. "Blessed is he who may call three his companion." Thanks for all the advice.

So glad out worked out and sounds like you did just fine.