Best thing to do is work with her, there's a reason for the behavior and there's obviously some negative associations with tying and unloading.
As far as the tying goes, work with her gradually, let her see that the pressure isn't bad. If you lead her around, give her a couple of yanks on her lead rope and if she's good about it and stands, then reward her with praise, or how you see fit. If she is good to ground tie and/or wont run off, let her wander around (supervised) with her lead rope on the ground once she steps on it a few times she'll get the idea. If all this goes well, and you see some progress, start gradually tying her with breakaway straps to unhook easily (like a trailer tie). for each time she is good, reward her with praise and let her know she's doing good, if she acts up, unhook her, correct (not aggressively that will not improve matters) the behavior and try again. It's going to take patience and time, but you'll start to see an improvement and be able to leave her for loger periords of time.
as for the trailering issue of unloading, I liked the idea of lunging her off the trailer until she starts to put two and two together. this will also take time to correct. Typically, on the farm I worked at we had the opposite problem, just took time and working with them.
I would say one word of caution, never unhook a horse through anything, a gate, trailer window, over a fence...anything, you never know what could happen. I only say this from experience, you never know what's going to happen, even if you know a horse really well.
Seeing as how I'm not a trainer, nor do I say with any guarentee that any of this will help, just ideas. There are some really good videos from the Parellis and other good horsemen on how to work through these issues, sometimes seeing helps when working through these things.
Hope it all goes well.