Ans1) - you can use a common source stage to use. To fix Vds , you should use opamp in negative feedback and one of the end of the opamp should ne the vds.
General thumb rules for plotting :-
1) W >> Wmin ( to start with 10 times say 10um for 5uA of dc current )
2) L= Lmin ( can start with that = 180nm )
Ans2) you must be able to plot with the method you described. You must have missed something.
Please share your experience , I am also very new to this method.