(1) I was pretty sure on every move - the small tips are really well laid out and, while unobvious, are clear enough if you have the right context
(2) Item use was very clear and felt really good!
(3) I didn't use hints besides the basic ones the game gives but they weren't completely necessary even then. It was a good "first level" to get to grips with the game.
(4) I wouldn't remove anything, if anything I'd love more to play with and perhaps some basic sound effects to give the satisfaction of the key hitting the lock etc.
I have my own playtest up if you have 5-10 minutes to invest at any point - no pressure to do so though!
Hope this helps!