Does soy isoflavones help you concieve?

Not significantly. The precise answer is that by altering your food intake, specifically eating more soy in this case, you could potentially increase your odds by a tiny tiny fraction, maybe 0.1%, you could be lowering your odds by a tiny tiny fraction, maybe 0.1%. In other words, it essentially makes no difference. There is no obvious harm in trying, but you would be better off adopting other strategies.
Not aware of this. Isoflavonoids may increase natural estrogens, but conception is more involved than just estrogen. See your doctor if you are having difficulty conceiving. S/he may order a plethora of hormonal tests and refer you to an infertility doctor who may perform further tests to see if the one with infertility is you or your partner, whether one is ovulating, and whether one's anatomy is ok.