Both methods are fine; I prefer scales strongly, because of simplicity of operation and no cleanups... I believe pretty much any .01g scale will be good enough for our purposses, e.g. I wouldn't get the widelly recommended lb-501 as it was many times more expensive to get it where i'm at than in the states, so I just bought a cheap 500/0.01g china scale for 20 bucks or so, and it's been perfectly fine and reproducible for my mixes. Later I bought another china scale to have a backup and thats good too...
I would probably pour all non-dropper bottles into there own dropper bottles, but most flavors have droppers, or atleast the ones i've seen/used.
Also, you can e.g. get away by using the cap to hold over the opening of the bottle and then adjust the cap so that there's just a very slight opening which you can then control better the amount that comes out, but it would be better to just place them in there own dropper bottle, or else have designated pipettes for each of those rare flavors... Ok, maybe they aren't rare, I dunno
Edit: Of course bigger flavor bottles often dont have droppers, sorry - I forgot!
