Sounds like you have been having fun building 4sqrp kits. To answer your NS-40 questions.
Yes, 9 watts out is pretty standard. If you want to stay with the 5 watts or less for qrp you can lower the voltage until you get to those lower output limits and it will also put less load on your output transistor.
Yes going to 7.040 is perfectly acceptable. Don't want to hurt kit sales but you could just swap out the xtals when you were wanting to go to 7.040 or rig a dual xtal setup as many have done.
Good luck with setting up the cables and getting on the air with your setup!!
cu es 72, Bart W0IIT