Not sure if the -7's are GTSS equiv - i always get confused, I thought they were the -10's that were the same as GTSS.....?
They are good for around 300rwkw safe, or pushing towards 350rwkw if you really get on them. Good turbo choice for a stock engine...
Get a nismo centre cluster gauge so you can tell the oil temp rather than guessing with the stock one - or a real oil temp gauge if you like. You want to keep oil under 120deg. If get gets over 120-125 you should be backing off to let it cool. But defiantly get a good oil cooler setup.
As for a tuner - Yeah pretty much what you listed, i dunno i just pay the money and drive my car I think with a stock ecu and stock turbos, they up the boost to about 1bar, put in a fuel pressure reg to lean it out a little, and tune it that way. You could look at getting a powerFC, they work well with the standard setup as well.