From what I've read on HACS, you will need a BMI under 30 for the All Nippon contracts. Otherwise if you aren't overweight, it sounds like it's a thorough physical with hearing/vision/blood work/urine test/balance tests.
On the subject of breaking the contract with 2-3 months notice...is it fair to say that you will never work for that contract company again if you do need to bow out of the contract early? The reason this is an issue is because company offered leaves of absence can be cancelled at any time. If that happens, I would be required to resign from my current company if I didn't break my contract the contracting company. I would rather not take the contract to begin with if there was going to be repercussions. It's not worth burning a bridge over.