Unclear. The effects of tooth bleaching while pregnant are largely unstudied, so experts recommend refraining from teeth bleaching to prevent possible birth defects or harm to your baby. Bleaching products also can be found in tooth-whitening toothpastes, so i would avoid them as well.
Yes. Yes but you should follow the instructions on the box if you are using an over the counter.
Maybe. It is probably safe. However since doing studies on pregnant women is unethical none have been done for bleaching. So it is impossible to give you a definitive answer. Try using the otc rembrandt deeply white line of paste and rinse. They are very effective together and may whiten your teeth enough for you to be satisfied.