the first line of your first post you say you need control arm ball joints , item 10 on this link called wishbone by BMW, items 3 & 4 on bavauto link .called control arm lower , complete with bush and ball joint .
the tension struts are as previously discussed .
you should ask the person who mentioned caster bushes exactly what are they refering to .

RealOEM.com BMW E53 X5 3.0d Frnt axle support,wishbone/tension strut