Usually, when I am asked to fill out personal info like Lyle had to do at check-in, I'm in a hurry and I don't care if they can read it or not - I just quickly fill in the blanks. And, it's usually messy, I link letters that I normally wouldn't. Plus, he's leaving them a wrong address - I think he perhaps just changed his handwriting as part of his "cover."
For the Room - he's sitting in his room debating what he is going to do, decides he should leave money for the room, calmly writes the note. I think this note is probably true to his handwriting.
Suicide seems to be larger and bolder - just like the thought. I think he wrote this when he made his decision as a reinforcement to his brain.
Just my thoughts.