You should share the gig on social media platform regularly after publish. To write gig description, you can divide this 3 parts. One is intro of gig, then your services and finally why any buyer choose you. I think its enough. Good luck
Only one device can hold on only one profile... if you ensure that, the buyer can't login his/her profile in your sold device, its fine. Other wise fiverr send you a mail for close one profile.