These guys are fairly good for tickling:
As are these guys:
Feathers do not usually work very well.
I'm gping to challenge you on this person, though: so you found a facebook and the pictures match up? If they're the same pictures then I can access those as well and pose as this person. If they're not the same pictures then it might still not be that person, maybe someone that knows her or someone that has accessed other accounts, or something. Even if it is that person, there's no reason to think that she will not take advantage of you or the situation. Assuming she isn't a no-show. The safest thing is to bring someone you trust and have them sit nearby to some degree, else let someone know where you are in case something happens.
Nervousness sometimes works in favor of tickling, sometimes not.
I haven't had a problem with being able to hold down a girl even while using a hairbrush. I'm not a big guy by any means -- 150 pounds, 5'8 -- so that's something to keep in mind. I'm not sure I would recommend bondage -- either tying or being tied -- with a stranger. She should be fairly cautious about it and I think you shouldn't consider being tied. Tying the ankles is probably fine and maybe the wrists, but I wouldn't tie or be tied down to anything.
People do get tickled out but sometimes they get more ticklish as time goes on. A lot of the girls I've played with have burned out around the hour mark, though one or two has gotten much more receptive to tickling.
Do meet in a public place, do confirm that they're still interested before you head out. Just be wary if that people are with her they can still hide or come later than her.
Feel free to message me if you have more specific questions that I didn't cover.