Could someone advise exactly what is PMI. If I request to cancel this does it have anything to do with the Homeowner's Insurance Policy?

PMI is there to protect the lender, not you. Lenders require PMI on high loan-to-value (LTV) loans. As a condition of providing you a mortgage, you're required to carry PMI at your cost until the loan reaches 80% LTV. If you believe your home has appreciated enough since you purchased it to get you to 80% LTV or less, it might be worth it to spend the $ on a new appraisal.

No it don't have anything to do with your Insurance Policy. When your home reaches at sure point in its time. You can cancel and it won't hurt you a bit!