N3 are a much more versatile float shape and construction than many would think. These are excellent whip to hand floats as well as good for short lining. Their very slim shape really does offer less resistance to biting fish and they strike through the water very cleanly. Their slightly longer tips help to read bites extremely well.
Most often used in very slow paced rivers, drains and canals these are actually also very good when used in flow. If you are expecting bites to come quickly and you do not need to slow or hold back the float then these really are excellent. They offer so little resistance that bites seem to be quicker & more positive. And when striking their lack of resistance, even in the bigger sizes, really is quite noticeable and especially when compared to a more bulbous shaped float typically used in flow.
Shotting depends on size and what you actually want to do and try to achieve but a bulk with some droppers when fishing positively is normally ideal. You can always move the droppers together or further apart and if the bulk is made of several small shot then you can move and spread those as well. Although the bigger sizes are best suited to the bulk being an olivette.