Advice needed!

So I think I found my horse! The lady who owns her desperately needs to get rid of her becuase she's getting divorced and she's losing her house and all that jazz. My riding instructor knows her and basically forced me to come with her to look at this horse.
She's (her name is Lacey) about 100 pounds overwieght, totally hot since she's an Arabian, and hadn't been ridden in 2 years but something about her just got to me. I think it's because she really reminds me of my love horse, a little POA that came to camp last year, crazy as can be, and through many hours of riding through spooks and bit changes (finally stopping at a rubber snaffle, he came in wearing a curb!) he has totally settled down and is now ridden by campers with no worries on my part at all. So this crazy horse calming thing is not something I've never done before and my instructor would be there to save me if I need it.
Evidentally Lacey has also been ridden in quite a few parades so she must be able to be calm enough for that. Basically her problems (we brought her and her best friend to camp on Tuesday so I could get to know her and start getting her healthy) are that she is really way to attached to her best friend horse, but I'm hoping that that'll go away once she settles in at camp, and that she gets way too excited on the trails. She's totally fine and serene in the arena so I'm thinking she's just never really been on a deep woods trail. Also, all her wieght seems to make it a wee bit difficult for her to balance herself correctly and the trails are not level so that could contribute to the issue.
She also gets really jumpy when someone gets on her back but that could be because of her weight since no saddle is really made to fit an obsenely obese horse.
I've been ridng her for 30 or less minutes a day in an English saddle (which is what she has always been ridden in) and a snaffle bit.
Any ideas about how to help her settle in and calm down? She wants to be calm, she just isn't sometimes...

Did you buy her? I think if you have the time, energy and knowledge to calm her, then go for it. In my experience horses that do well in an arena but freak out on a trail, will always freak out on a trail. I'm not a horse trainer though and don't have the inclination to turn a spooky horse into a good trail mount.

It's hard to say without seeing the horse to know weather she is spooking because she is unconfident and buddy sour or becuase she is just generally a spooky horse. I do think that with an experienced handler and good leadership she could calm down quite a bit. An experienced rider knows how to handle a spooky horse on the trail. If you trust your trainer and she will be there to quide you all the way it's worth a shot. What's the worse case scenario? The horse ends up being to much for you and you sell her? At least you will gain some experience while working with her and will probably learn a lot with your trainers help.

Thanks for replying. I'm being gifted her if we work out. Basically the lady wants to find someone Lacy clicks with and if it's me I get a free horse with a barnful of hay and lots of horse gear. It's a pretty sweet deal.
So this last week I've been working with her a lot, not taking her on rides or taking her best friend anywhere, just lunging her (which she absolutely loves) and working on getting her weight down a little bit and building her bond with me. On Friday I ponied her off her best friend so she would get out on the trail in a calm controlled fashion and not have worry about her surroundings AND a rider. That worked pretty ok. I think she should be even better in a couple of weeks.
Thanks for the advice. :)