Hey, thanks for all the kind feedback!
Regarding the first issue you brought up, I'm completely clueless. I'll do some more research on that area and inform you once I find out.
I'm already aware of what's causing the second problem to occur. I messed up in making the collision hitbox and that resulted in it not being on even level with each tile, meaning the player would technically walk against a wall. Here's a screenshot for further clarification: 
As you can see the tiles are slightly off resulting in this situation. Quite unsatisfying if I say so myself :P
Once again thank you for all the kind and constructive feedback, even going as far as to send screenshots of any errors that may occur whilst playing the game. People like you are a godsend for us developers, so thank you :)