Isn't Laci short for Laszlo? Like Bill and William. So wouldn't A also be correct?
Yes it is.
Yes it is correct. Laci, Lacika, Lacó is also
Difference between "Jo" and "Jol"
Could you please use full sentences? It sounds a lot nicer than just phrases.
And an answer in a full sentence:
jó means "good"; it's an adjective. jól means "well"; it's an adverb.