It depends on what kind of country you are hunting in along if you are using a stand or not. I restrict my shots to 30 yards or less. But then I also will spot and stalk to within that distance or use a ground blind in heavy cover for deer and elk. The shots that I have taken have been anywhere from 5 yards to just over my 30 yard limit.
i try to stay within 40 yards.thats my comfert zone no need to make a bad shot and wound a animal. but then theres gyes who have bow hunted for a long time that can make 40+ yard shots. arrows are hard to find when they go to far and there too expensive to loose.
Really has to be up to you. You are the only one that knows your ability to make a clean kill shot. Practice, practice, practice! Don't be afraid to push your limits while practicing, really helps with accuracy and a better confidence at closer ranges. Starting out I didn't feel comfortable shooting at an animal over 20 yds. Now I feel confident to 40, and won't attempt anything much past that. I can make shots past 40, but too many variables the further out you get.
When it comes to scent, there are basically two types; those that attract and those that mask. I've tried both on many occasions. There are lots and lots of "doe in heat" scents, designed to attract a big buck into range. I've also used a "cow in heat" scent while elk hunting.
Another scent would almost be better named as a "coverup smell". The main goal is to cover up human odor or mask it. Though I don't believe you can ever totally eliminate all human...