yes, ias outside of weapon effects JAB speed, not fury though.

(100% ias=4.5 jab, 170% ias=4.0jab main -10 base speed bp's anything slower is usually inadequate)

yes, ping matters a bit
25 ping would normally beat 250 ping if same class/similar build/gear

javalins damage is boosted by both STR and DEX at a rate of .75% ed for each 1 stat placed into str-dex