WOW, too legit!
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Updated to Version 1.02 which has double jump and an experimental wall jump which I'll likely still have to adapt a bit. I have included the Source for 1.01 which uses triggers for the wall jump.
that's built into GB Studio, when you draw your collision squares, there are custom ones such as collision top, left, right and bottom. that way it will stop you from the one side, and let you pass through the other.
all the above that you’ve mentioned is definitely possible.
For all the platform things you’ve mentioned all you need to do is make a second actor and then swap his position with yours and your sprite with his, then you will be able to do most of what you’ve been asking.
As for the level going from left to right, I’ve actually make that mechanic on the second level of my game called ECHO (see my itch page) where I’ll be happy to share how I did it in a couple weeks.