1.u will know if u hit a vain. u wwill twicth and feel it
4.pull just more then enough oil into your siringe, then pull it out of the vial,hold upright and squeeze air out(flick if you need to)
5.23 gauge needle is fine for oil base even 21 if you get desperate but use a new tip for injecting /pulling out of the vial.oil takes a little while to go in, could take 5 -15 secs.it will seem like forever
7.1.25ml then wouldnt it be