Meh on the tubing. Cheap but there is better. Primochill LRT is awesome!
The 355 pump is 3/8" barbs. You have to buy an aftermarket top for 1/2" barbs. The MCP655 is native 1/2 built in barbs. The 355 is better than the 655 with a XSPC pump top. Look at the XSPC restop for the 355.
The RS360 is an older design. The RX360 is MUCH better. For a CPU only loop the RX360 is plenty. You mention a CPU and GPU, which ones? IT MATTERS A LOT! You don't want to underad.
You sure don't need those monster high CFM fans. Hopefully they will undervolt well.
Either fan controller is good, but you should get the 30W one if you plan to run the fans in series on one knob. Those are pretty high wattage fans.