I don't know what size your is coupon but the minimum safe margin is 0.0625 inch (1/16"). And that is really the ultra minimum only for very small prints. Normally, it's 0.125" (1/8") and that's better too.
You can put your border within the 0.0625" all around your document but that's really thin and "dangerous", so if it looks nice on your design with a thicker border, use thicker. Bleed should also be 0.125" but sometimes on sticker, depending which process the printer is using (rolls or sheets), 0.0625" can be acceptable.
Again, if your coupon is big or the layout permits it, use the safe numbers for bleed and inside margins: 0.125"
The same specifications apply for the peel-off stickers than any other stickers or custom diecut project.
Thickness of a dieline
The dieline is the line on your document that represents the custom shape of the sticker.
It will not be printed on the sticker but used by the printer to build a matrice with razors.
For maximum precision, it should be 0.3 points thick. The matrice is the diecut.
You need to use a spot color and name it "dieline" to make sure it won't be printed or provide it on a separate file with this outline only, centered and in the exact position and alignment of your design. Use registrations marks (trim marks) to makes sure it's perfectly aligned.
Provide a JPG proof to the printer that will show the dieline in a bright color, and the design together. This way he can see what you expect as final result and if your dieline is alright.
You have 2 options if you want to print that dashed line in bleed or non-bleed. I made an example below. The non-bleed version would give better results if you don't know if the printer is a very good one because any misalignment during the diecut phase will not be too visible. And if the printer uses rolls, the misaligned printing won't be too visible either. Plus it's cheaper.
As you guess with bleed, that kind of border doesn't look good if the printer doesn't adjust his diecut well. Some sides of the border could look thicker than the others.
PS: Sorry for the inch units, you'll need to convert them to the ones you prefer!
Stickers printed on rolls:
Stickers printed on sheets and diecut for shapes:
(diecut = probably what you call "razor"). The metal part on top is the diecut.
Sources: Rolls: Youtube.com user Peng Nicole, Sheets: go-media.com