Yes, vape as needed.  I normally do 4-5 in a row.  I think it is because by the time I am drawing the fifth, the first is hitting my system.  When I do finish my 4-5 draws, I sit my PV just out of my line of sight.  I don't want to get that habitual about 
vaping.
About every 2-3 months I would drop down a little in the nic. I might vape a little more for a week, but I just don't have the time and my body just got used to it.  They are small steps anyway.
Yes, vape away.  My doctor said it was better than smoking.