How long should it ferment?
-- until your gravity reading is consistent for 3 days
If I take a gravity reading will removing lid from my bucket and getting the reading the correct procedure?
-- yes, popping the top for a quick gravity read should be fine. If fermentation is complete or mostly complete, the alcohol in the beer reduces the risk of any bacteria being able to get in and do damage.
When should I dry hop?
-- when primary fermentation is completed
Should I use a secondary ferment to dry hop?
-- most people do, you don't have to though
If I use secondary ferment bucket do you filter as you pour it in?
-- rack it in gently to minimize oxygen exposure. Don't pour it in.