Is boron good for boosting testostrone?

It doesn't directly boost testosterone production. What it does is prevent sex hormone binding globulin from locking up testosterone in the bloodstream so that it can be used. If you have your blood checked and they give you only your total testosterone levels, it doesn't help much. Free testosterone is what matters and in males, normal levels of free testosterone are about 2-2.5% of total testosterone. The rest of your testosterone is bound to SHBG (as explained above) and the rest is usually bound to albumin (though its not a hard bond like SHBG).

Is this product vegetarian?

Boron is a mineral, so unless they used packin' mules to gather it, I would say no.

Have any female users noticed hair loss form using this supplement?

Actually, funny you ask that question. I was using the 'Now' brand of Boron (its all the same) and after about a year, i have lost some hair. That may not be due to the boron as much as is could be due to an increase in DHEA (which is caused by an increase in Testosterone). However, to make Boron effective for a test boost, you must take more than 3 mg per day. I have been taking 15mg per day as science supports dosages up to 20mg/day. I am not a physician, but DO NOT take more than that as it can be fatal. That is why I take 15mg per day (to stay well beneath that maximum daily dosage). I probably need to take another supplement that regulates my DHEA levels as too much can make your hair fall out. Hope this helps.

What the % of the extract?

Boron is a mineral, not an extract. There are three different boron chemical sources in this because some forms are more easily absorbed by the body than others, per personal opinion? If you use this formulation, you should be able to get your boron requirements.