NewkeepsR 20g/18g/16g G23 Titanium Press Fit Threadless Push Pop in Labret Lip Monroe Tragus Earring Stud Piercing

When inserting this into the tragus do you put the back on first then insert the front stud?

Would this be safe to use on a slightly closed nose/cartilage piercing?

For the "2 pcs-20g earrings studs 2.5mm tops" option, does it come with two earrings or one earring? i have a double helix so i need to have 2.

How long is the post got the 20g or the earring?