No one can predict exactly what T will do for you. Will you pass? Most likely. I find that we (as in other ftm's) can pick out other ftms easier (or think we can...like gaydar) because we tend to obsess over gender and passing. I really don't feel like the average person picks apart our characteristics the way we as a group tend to. Someone else may disagree with me on that though.
I can't really answer the second part because I am not on T. There are a lot of great youtube videos out there about dating. ReeseKelly has one that is pretty good. Will some lesbians accept you and date you? Sure. But you need to think about whether or not that is something you really want....as lesbians tend to be attracted to females, and the more andro side of you as opposed to the masculine. Of course, people are all different. There are a few guys on youtube who I believe started out in a "lesbian" relationship and are still with their partners....one for 2+ years after being on T. Are straight girls ok with dating ftms? Sure, if you find the right one. Honestly - no, not every girl you approach is going to be okay with it. Some might be weirded out. Some might seem okay with it, and then not be. Some might not think it's an issue at all whatsoever and you will live happily ever after with that person. For the ones that aren't okay with it - you just need to let those ones go, and move on to the next one. To answer what I believe you are essentially asking....No, you will not be alone forever, and yes...you will find someone who loves and accepts you, it just may not happen the first try.