mechanical questions about kalista

im playing kalista for a while now,mostly for fun,without any deeper input.now that the new (and hopefully limited) skin is out,i thought id deepen my understanding for kalista a little more.farming with her goes pretty well,as im an adc main,my problems are rather the use of her passive aswell as chases(i can Q walljump and Q cancel though)

questions i have are mostly about her autoattacks(but not entirely),and they go as follows:

.)how do i properly do the backjumps(autoattack into martial pose(jump)) backwards,without loosing my target and walking,or worse,standing still entirely

.)does the attack command help weaving jumps into the autoattacks? if yes,how should it be used correctly?

.) there is no max to the ammount of rend (e) stacks a target can have,but does the damage still cap at some point due to spears disappearing again? im unsure how the damage calculation works with rend aswell

.)is there any given rule on when to max E and when to max Q first(or is it always E?)

.)at which point (in atk speed) is it better to just auto than use the jumps?

kalista main,i summon thee,help me in my demise. other people with sufficent knowledge are welcome aswell of course

thanks in advance