Not bad. Yesterday on Amazon (I have Prime) I got these 12x500ml for $9.87... for some reason they're selling for $21.97 today so I'd definitely go with your choice if I didn't get them cheap.
But to be honest, 500ml is too big for 1 - 3.5g of weed per jar. Ah well.
1) how much is totally up to you. Since you're really new to it, probably as little as possible. Grind up a small bud and that'll usually be more than enough for you at a time to start. 2) Since you don't have a grinder, get it to the point that you could easily pour it into a gutted pen. 3) Doobtubes as mentioned by another posted are super handy, but really any kind of jar that has an air tight seal (mason jars are ideal for storing cannabis). I'd recommend having one for your clean bud, and another for your roaches. These kinds of jars are hard to beat, and you can easily get smaller ones at a dollar store.