XQS runs 6mg up to 17mg. Because of that, there is usually more than one level of the same flavour. If pouches are new to you, start at the lowest and work up instead.
Yes. Mix and match any three XQS pouches for £12. Moreover the flavours can be mixed freely, so you are not tied to three of the same tin.
No. They are tobacco free, so they give off no smoke and no vapour. Consequently you can use them where vaping is not allowed, such as on a train or at a desk. The filling is plant fibre with nicotine and flavouring.