Sometimes when I talk to someone, my vision gets really blurry and I get really dizzy. Is this normal?

No. This is not a problem with your eye, but with your circulation. The parts of the brain that control balance and sight are not receiving enough blood. It can occur with fainting, but there are many other possible causes. If this is a recurring problem you should discuss it with your pcp.
Usually not. Blurred vision and dizziness are not normal effects of prolonged use of the eyes. There is often an underlying cause such as dehydration, fatigue, certain infections, and several other conditions. If this persists, you should have a general medical examination.