Rotor offset is indeed different. I did the swap on my old car and found the easiest way was to swap out the entire knuckle/hub assembly for a 2L one, plus calipers and rotors. Otherwise you will have to space the rotor out from the hub, meaning longer studs probably required, plus increased scrub radius etc.
The difference:
Also correct that it will require 16" rims unless you want to get happy with a grinder (and potentially stagger pad changes so you always have one worn pad and the caliper sits that little bit more compressed. Too much stuffing around for me, I just ran 16s and lived with the slightly limited tyre choices.)
Can't comment on the booster, though I wish I'd thought of it when I was doing the upgrade!
As for whether it's worth it... depends on how you value your time and effort. If you can get the parts for less than a couple of hundred bucks and are handy enough to do it in a few hours, then probably. It does make a noticeable difference (I was running rear discs too, but did them at different times so could spot the incremental improvement.) It's not going to be mind-blowing, and not going to have you locking up as soon as you think about braking, but it is an improvement.
yep as darky said, speedy desert rats in 15x7 & -15mm + flap disk + staggered pad changes = 15's on a SV