Yes, definitely tell them you have a sore throat. Actually, if you get to the hospital or office on Monday and still have that sore throat (or a cold or infection), they may not go ahead with the procedure. They usually like people who're having routine procedures to be in well health before the procedure just so the risk of any complications is as low as possible. Here where I live, asking whether you feel well that day and taking your temperature is a standard part of the pre-procedure workup.

It's unlikely that you'd bleed from an endoscopy, but you want to keep that likelihood down. If he's scoping you to see if you have ulcerations or, say, herniated blood vessels in your esophagus, among other things, any irritation to the mucosal (surface) layer could increase your changes of bleeding, and bleeding into the esophagus isn't a good thing, especially when they have a tube down your throat. It would not only make their jobs harder of detecting any problems; it could also cause you to aspirate fluid and complicate potential breathing problems, which wouldn't be good when you're heavily sedated.

Definitely tell the doctor how much weed you smoke and how much recently. That'll help them adjust the dosage of your sedative properly. Fortunately, Monday's not very far away, so after the procedure's over, you should be fine to enjoy your purps. Good luck!