Simple amplifier circuit, norton, thevenin questions
For your first question, yes of course that's how the thevenin and Norton equivalent circuits will look like , the main concern is how to find the value of Vth or Ino and Rno.

I don't think Vth=V1 and we must consider the gain of the opamp to obtain the correct Vth equations. The link provided in the comments by bss36504 makes a lot of sense as it takes the opamp out and replaces it by an equivalent voltage source. Once this is done it makes things  lot more easier. For that you should first derive the gain Vout/Vin with just Rs in the rigt hand side. With Nodal analysis I think this should be possible.

In your formula that you have tried to derive I think you have missed Iload in the 3rd step.