1) Find Norton and Thevenin equivalents.
2) Use a series of Norton-Thevenin and series/parallel transformations to reduce a circuit shown into the single-loop circuit. Then, find current I. (Current I is between two nodes at the botom of (1) circuit!)

I have got two exercises which I try to solve.

Thanks for help in advance!

 

for problem 1)
You seem to have almost all of the correct steps:
step (2): you left out your output nodes, what is the resistance seen across it (it should be across the 2ohm resistor
step (4): what is the voltage across the output?
step (6): In this step, it appears you have changes the output port. Make sure it corresponds with the previous step.

for problem 2:
all of your steps appear to be correct. Now just short your open port.
You can then combine the voltage sources and find the current.

 

I edited my answer because I was originally unclear on the prompt for question (2).