One temperature doesnt mean anything. Its the overall pattern throughout your cycle that you need to look at. Everyone is different and many things can alter your temperate day to day.

It has to be elevated for 18+ days for you to be pregnant. It's normal for your temp to be elevated for 14 days after ovulation. 

You can start now or once you get your menses. You just need to do it in the morning when you first wake up before you do anything else. It should Approximately be at the same time every morning. Record it and watch the trend. It will help you determine when you ovulated and can help determine if your pregnant as your temp will remain high as you approach the beginning of your next cycle however this can't confirm pregnancy obvisously

You don't need a special thermometer to take your temp. And it's hard to tell off one reading. You really need to do it consistently for a whole cycle to get a trend