to summarise
the stock rb20 turbo has a ceramic exhaust wheel, the general consesus is that this will break due to a combination of heat and revs if you run 1bar (some say anything upto 1 bar is OK). I'd say the safe limit allowing for hot days and cold days is 0.9bar (std is 0.8ish).
at this level of boost the factory ecu will dump alot of fuel in for safety and you'll get crap fuel consumption (i got ~10mpg!) so running lean wont be a problem. the other side effect of running so rich is that you lose a fair amount of power.
so to correct the fuelling you can either fit a piggy back ecu like a SAFC and trick the factory ecu into supplying less fuel or get a mappable full replacement ecu like a Power FC or as bigblue and martinc say get your factory ecu "chipped" or "rewritten" - personally i dont know anyone in the UK that does this for the r32gtst - and i would want to get any "off the shelf" map checked on a dyno as every car is different.
its only once you have a mechanism to fix the fuelling that you need to watch out for running lean and causing damage.
have a read of this thread on SAU and you'll see what power people have made and what mods they used.
http://www.skylinesaustralia.com/forums/index.php?showtopic=103095