I would suggest getting a 16 ga luer lock syringe for filling the tank... That 9 ml juice bottle will take forever to drip from the smaller squeeze bottles and if you get the 30ml or bigger the top they give you is useless...
No need to thin I have run Gorilla in my Vmod XL and had no issues.... Just when you feed, every so often take of your drip tip and give a bit of a firmer one (wait for the bubbles) then right the XL and give a firm squeeze again... Release slowly... You should see juice come up and flood the atty then suck back down... Give a couple of quick squeezes to suck excess juice and vape your head off...