I don't know how much help I can be here, but I'll give it a shot. In my admittedly limited experience, mostly in New York City, about thirty years younger and looking at tech jobs, what matters most to an employer are that you're a good fit for the job, and that you get along comfortably with your potential co-workers. When things of a more personal nature have come up for me at work, it's basically been either curiousity or my employer wanting to make sure they could depend on me, that I was a together person and would continue to do my job well. From what I understand of the modern job market, you may have a harder time overcoming age related descrimination than any related to your (trans)gender(ness). That said, if the job you're looking for is very much customer facing, it could be a lot more hit or miss, and I can't entirely fault employers for not wanting to hire someone who they feel would make their customers uncomfortable - it's a social problem at it's root.
Keep in mind too that you may not need to reveal your status to your interviewer or potential co-workers - generally the person or people in HR are the only ones that are going to need to know, if that's a route you want to go. In my life at least, a little patience, willingness to talk in a limited fashion about my transgenderedness, and not letting my transgendered nature dominate who I am has gone a long way to keeping things from getting hostile. Then again, I've also probably been unnaturally lucky; From what I read, too many transfolk have suffered under similar circumstances.
I guess my advice boils down to this: Don't alet your trans* nature become a big part of getting a job, and it probably will stay a minor issue. Good luck with the job hunt!