I've never seen Stubbs here in Canada, could be I wasn't looking.
It's not a very flashy package.....I've missed it in stores before....
"Now I have to learn to use them. I've read about how briquettes are better for longer cooks so I'll try something longer. One question, if I add more during a cook do I have to light them first or just stick them on top of the already burning coals? Why?"Here's the way I think about it:
If you want to maintain the temp you're at & increase the length of cook time, more or less, add in unlit....
If you want to raise the temp you're at (& extend some) add in lit.....
You can add K Blue unlit......just add onto fully lit areas so it burns right away, or, add to the end of a chain (snake) so it gets to heat up before catching.....the in between, adding to a partial / smouldering area, will cause "the stink"........
Stubb's is good for the long burn, but Blue K's will still work fine, just avoid getting to a dying fire situation......