a] you need both dry condition to avoid hydrolysis of acid chloride
and you need a base (such as pyridine)as well, just to trap the HCl and thus preventing revrsible reaction
b] You can do that, but it will be at the expenss of yield(very low), moreover the acid will protonate the aniline's nitrogen more than the oxygen one, that defenitly will weak the nucleophilicity of nitrogen to attack the carbonyl
c] the best ratio is 2 (amine): 1 alkyl halide