What does the manufacturer reccomend? For my Mathews it is 5 grains per inch so for a 70 pound bow that comes to 350 grains. The arrow itself will weigh less than this becaue you have to figure in the broadhead, fletching and nock in the weight.
I think if I remeber right 5 grains per inch is a pretty standard number for all bow makers. I beleive if your arrow weight is under 350 grains tthe bow can explodeon you. I think to keep things safe I would try to get my arrow weight around 420 grains. For one your bow will be just that much quieter. I pull 67 pounds on my Hoyt and my arrows weight 450 grains and it sounds like a truck hitting a wall when the arrows hit their mark.
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...