"Quickly" is an adverb, and is used to modify a verb. "Am I running quickly enough?" "If you want to catch the bus, you will need to run more quickly." I am running (verb). In what way I am running? I could be running quickly, slowly, gracefully, powerfully, clumsily. "Quick" is an adjective and is used to modify a noun. "More quick" is wrong, or at least uncommon. You would say "quicker." There is a novel entitled "My Gun Is Quick." Gun... noun. What kind of a gun is it? It could be heavy, small, accurate... or quick. One could imagine a duel: Hamilton says "My gun is quick," Burr says "Yes, but my gun is quicker." "You've got any more bread" is incorrect as written. "Have you got any more bread?" is correct. It could be used this way. The host puts bread on the table. The guests eat all of the bread that is on the table. One of them asks "Have you got any more bread?" It means "is there more bread, somewhere, in addition to the bread that was on the table?"

to answer questions 2 and 3: you probably want to look this up in a good grammar text, but here's my take as a native speaker (not teacher) of English. 2. Just vs simply - 'It's just a phase'; 'it's simply a phase'. When modifying a phrase, to imply that it is not very important, you can use either just or simply. Just is normal in speech and less formal writing. 'Simply' has an old-fashioned ring about it. It is still common in instruction manuals and possibly in politician's speeches 'That's simply incorrect' where most of us would say 'that's just wrong'. Note that when you're using simply as an adverb from the word simple, you can't replace it with just. 'He spoke simply (ie in a simple way) and clearly'. 3. Just vs only: Again, just is less formal. You would write 'there's only one left' but you could say either 'there's just one left' or 'there's only one left'. 'I'm only going to the shops, I won't be long' or 'I'm just going to the shops, I won't be long'. 'Just' has a slightly more colloquial feel but it is not impolite at all. 'Just' can also be used to mean 'I'm about to do', so in speech "I'm just going to the shops" could mean "I'm only going to the shops" (nowhere else) or "I'm about to go to the shops", that is, I'm in the act of leaving to go to the shops now. Context gives the key. Only is not used this way in most dialects of English.