My car hasn't been tracked, but compared to a big rear sway bar on a mk2/mk3, the beam setup behaves very similarly.
I can't speak to the tire life portion either because in the time I've had it on my car there's been multiple sets of wheels and none on long enough to tell if the beam made a notable difference. Bryson is the only other person i know that has run one on the street and track, and he tracked his car quite a bit so he'd have better on track info. If you could still get a hold of him.
You can pre-load the bars, but it will change the rear alignment. My car was setup with the bars "neutral" and the alignment set to as close to vertical (0* camber) and .5* toe in, IIRC. It's been so long I don't recall if those alignment specs are accurate though.