Are you a Chinese national? Perhaps not. If that's the case, then you are an overseas hire.

The truth: rarely pure and never simple. Doesn't sound as though you'be been blacklisted, yet. It sounds as though your rep is doing his/her procedural checks. Get a letter from your most recent employer - the one with whom you had a positive relationship - and have them send it to Search. Or alternatively, have Search contact him/her. Failing that, follow Psyguy's subsequent suggestions. It's worth remembering that Search doesn't pretend to be a non profit organization, and that there are now many agencies chasing the same penny.

Cut off point at most international schools (in Thailand) is sixty. Only exceptions are if you're already 'in' and teaching a subject where it's very difficult to find staff. Suggest subbing if you're really keen. Otherwise, it's EFL work in Thai institutions - and probably outside Bkk.

It's not 4%!
Sliding scale, based on income, up to about 30%. The highest rate will certainly include teachers at most international schools.

The original post specifically asks for advice on the fairs:

"I am looking ahead and deciding which job fair to shoot for...Any info/experience with the fairs?" etc.

Presumably anyone with half an ounce of intelligence and/or initiative would be exploring all the other avenues for finding jobs, including direct applications, TES, TIE, ad infinitum. Search Assoc actively caution people that the Bkk fair is really only for candidates with previous I.B. experience.

Extremities. The best motorcycle helmet and socks you can afford. Anything in between, you can buy on arrival.

Shoes, if you're anything larger than 'petite'.

There's an I.B. PYP (and MYP next year) school in Erbil, Kurdistan, Iraq: Bilkent College.

Search's database directly resulted in my previous two international jobs and recently provided the next one. The recruiting fairs are a mixed bag; subject to the vagaries of multiple variables. Attendance at one fair is included in your subscription.

"...whether these schools call themselves "for profit" or "not for profit," virtually all of them are actually for profit institutions and run themselves accordingly."
There you have it.

Anyone use this fair in recent years? Successful or...?

The short answer is "No". Any reputable I.B. school would pay for, or facilitate your training.

Suggest that you apply independently of any recruiting agencies, targeting schools you're genuinely interested in. Begin prior to the Christmas break. An I.B. maths teacher should have no trouble in finding a job. Search Associates are good for their database.

No need for a job fair. Recruiters will contact you!

Survey your staff. Keep it as short as possible but allow open ended responses. Find out how they feel now - what their main 'concerns' are, what they want for the future and realistic suggestions of how to reach those goals. Allow anonymous replies. Above all, never mistake silence for complicity.