Originally Posted by Tall_Yotie
Yup! There are buckets with a spigot near the bottom. If your bucket doesn't have one I would suggest getting one. Some brew shops can modify your current bucket. The spigot allows for sampling as well as easier transfer to a bottling bucket or secondary without risk of oxidation.
That seems to be generally thought of as a bad idea. The spigot can be hard to clean - which could mean a higher chance of infection. They are also cheap, so they can start to leak. A small leak might be fine for the 20 minutes of bottling, but it'd be a problem if it's sitting for a week+.
The chances of oxidation by opening the bucket is extremely tiny. There's a nice layer of CO2 there. Your biggest risk is something falling into the beer, and causing an infection, which is still unlikely.