How do I know? I can point you to a dorm room with grape juice stains on the ceiling... '-)
I've used all the tricks except for laying out to buy airlocks--put the lids on just loose enough to vent slow but keep any nosy gnats out. Found out accidentally by keeping the fermenting jug[s] in ye bathroom no gnats are attracted. Probably because they're all dead for some odd reason.
Also, leaving some airspace USUALLY [heh] means it won't fizz over if yer lucky, but I put my started jug in a basin bowl just to be safe.
I've also used white sugar, brown sugar or honey--whatever's in the kitchen to get things going, but good Welch's grape juice in the jug does have enough sugar to turn out ok. Welch's frozen concentrate needs some extra sugar/whatever added, though.
It's fun makin' your own potables. One of these days I want to try making some small-batch hi-power stuff, if you get my drift... [Any tips on such a subject would be welcome.]