Hi andras, a couple of different things happening for your #1

First thing - for blending it is a good idea to blend between 2 open edges.

But your blend target does not have an open edge, it is a solid. I'm talking about this piece here:




There are 2 faces that are connected to an edge in a solid like that, and it will be kind of random which face will be picked to be the blend target in a case like that.

To make it not random, it is a good idea to select the top face of your solid there and delete it, that will help to clarify that the vertical face is the blend target, because that will then be the only face that is attached to that edge.

Some more info in a minute...

- Michael