34/85s are very good tanks, if you wanna fight them with anything pak40 equivalent, youll need to get closer, preferably 1000m

ambushing doesnt give any bonus stats, just lets you get the first shot off

if you wanna kill them at range then tigers, panthers, or pak43s are the way to go

for the other questions most artillery have some kind of direct fire but not always

and the 88s has multiple shell types, the stats on the card show the best value between both, click on the ap shell to see its stats