Does the 727 support a full save state like the 757
No. Captain Sim do not provide a way to save a "panel state". I don't know which 757 you refer to, but it can't be the CS 757. Perhaps in the future, they will provide a way to save the 'panel state'.

i know they say you should use a default aircraft but i dont fly them as i would rather go through the full check list on start up and use a fully shut down
Having the default flight set as I described previously, does not mean you start FSX and load that particular flight before switching to the 727 (or whatever aircraft you choose). All it does is set a simple Cold-n-Dark setting as the norm.
So if you were, while on the FSX Start page, to switch the aircraft to the CS727-100F, then changed the airport to a bigger airport with a cargo ramp, then press FLY NOW, you will find that the CS727-100F is in a Cold-n-Dark panel state ayt the new airport and cargo ramp.

Flight1 offers an FSX Safe Start up flight which is recommended for advanced add-on aircraft. Although I haven't used it, I believe it is very similar to the default flight I suggested.

Hope this helps.

Mark