Almost always. Symptomatic fibroids are one of the most common reasons for tor myomectomy (removing the fibroids from the uterus). Generally, these are covered if symptomatic and other simpler treatment options have been tried but failed; for example, birth control pills, an iud or birth control shot.
Yes. If you are having symptoms from your fibroids that require treatment than the condition is medically necessary and your insurance will cover it. Just how much coverage you have depends upon the type of insurance plan you have and factors such as how much of your deductible you have already met for the year. You can probably check the details of coverage through your insurance company's website.