Sometimes. Although amenorrhea often signals that ovulation isn't happening, you shouldn't assume that you can't get pregnant just because you aren't having regular periods. If you are trying to get pregnant, and have questions about your cycle, you should see a healthcare provider. Similarly, if you aren't having periods and you did previously, you should get checked out!
Unlikely. If your brain isn't signalling for an egg release from your ovary, you won't have a signal for your periods either; that's usually the cause of amenorrhea. Often it's a hormonal imbalance--Thyroid, Prolactin, LH, FSH, Hcg should be checked. Your doctor can also induce a period as well w/ OCPs. If you've NEVER had a period, you should get an US to make sure you have normal uterus/vagina/ovaries.