Don't worry, you will do great!! I hope you update us when you find out your results!
The sample questions won't affect your NCLEX. When the test shuts off you get a screen telling you that you finished and that the next questions won't affect your score. Then you get some sample questions that they might implement in the coming years if test takers do well on them. They are formatted differently than the current SATA, multiple choice and ordering questions. They're basically having us sample possible templates to see how they go over with test takers.
They were pretty hard, so I'm glad they don't affect our scores! They also may never end up implementing them if the test takers do poorly on them, which I definitely did.
I hope I didn't make you too nervous! These sample questions are not graded and do not impact your score at all so you will be totally fine. I used UWorld and found the questions and format to be very similar to the NCLEX and that helped me a lot.
Again, good luck and we are all rooting for you! You got this!