First Volvo just purchased!

[hrahn]

Congrats on your Volvo!
Regarding the reset: no, just resetting the codes is not the same as removing power to the ECU.
When doing the latter, the car WILL probably idle like crap the first time you start it up, you will need to drive it fast/slow/gentle/hard (all kinds of driving) during the first approx. 50km after reconnecting the power because the ECU re-learns the specific settings for your engine and adjusts itself (it has a default setup on which it is running right after the reconnect, but that is far from optimal).
Apart from that, do the vacuum hoses. Just replaced mine a few months ago - it made quite a difference. I used thick-walled silicone hoses for easier routing for the little ones and stock Volvo ones for the intercooler hoses because I have the old intercooler setup and there are no Samcos for that.