Check out ka-t.org for SAFC settings and all things KA turbo.
250whp is possible with the t28, but not at stock boost (may need to upgrade your MAF too).
BOV location is a matter of opinion. Most use the hotpipe.
You need to at least retard your base timing a couple of degrees. If you want to turn up the boost, I suggest getting an MSD BTM or ECU tune. Too much timing + boost = broken stuff.
For an affordable, proven boost controller, go here
http://www.voodooboost.com/boost_con.../Voodoo_I_MBC/