Great score on the OEM struts. All of the suspension parts on my car are factory original and I'm at 185K miles. From you description it sounds like your suspension is getting pretty tired. We rarely salt the roads here so that must be why my suspension is in such good shape.
IDK about the poly bushings, but some people think they might be too stiff and cause a harsh ride.
There are some stiffer parts that can be used from the Audi parts bin, such as the Audi S3 control arm bracket with bushing:
https://www.idparts.com/ball-joints-control-arms-c-36_179.html
For the other bushing, the OEM one is probably a good choice.
https://www.idparts.com/control-arm-front-bushing-a5a6-p-4818.html
For ball joint, the Lemforders are actually fine and will last at least 200K miles.
You need the control arm mounting bolts as well as the strut tower bolts that are not in the kit you bought.
You can go here:
https://1stvwparts.com as a reference for illustrations. Just select your car and go to suspension to get the OEM part numbers to use on the IDParts website. The illustrations are extremely helpful for figuring out what parts you need.
Many of the bolts a one time use TTY bolts that can't be reused but if the rust is as bad as you implied, you might as well change them all. I'll look in my Bentley's tomorrow to see what bolts could be reused. ZZZZZZZZZZZZZZZZZ