Hi Preston and welcome! To foil or not to foil is a debate for the ages...there are as many who do as there are who don't. If you're trying to get a better bark, you probably don't want to foil. If you let that brisket ride all the way to finished internal temp (somewhere between 195-205...each piece of meat is different), you'll get a nice bark. It sounds like you already learned about one of the favorite sayings around here: If you're lookin', you're not cookin'. The best way to get if finished and get a nice bark is keep the smoker door closed. As far as when to stop adding smoke, that's a personal choice based on taste and experience. I like real smoky flavor, especially on a brisket, so I tend to keep the smoke rolling as long as its cooking. Others prefer much less smoke and adjust according to their own preference.
Good luck! Half the fun is in experimenting and learning about your own equipment and techniques as you go.
Red