P: 1px Transparent Border issue

You need to set layer position left top corner to whole pixel value and width and height also to rounded pixel value. And check if you have snap to pixel enabled in Photoshop settings.

HI. It's not only rendering issue, because if i move layer up and move, then layers underneath is half visible on that 1 pixel border. It's frustrating because photoshop dosn't have this issue long time ago, and now I have to duplicate layer few times to remove that border.
I'm using automatic sampling for resize.
The previous image had solid edges.
Here is png version after resize. You can download it, switch to RGB, and put some saturated layer below.

There might be almost transparent half pixels. If you resize bitmap.

This could just be a rendering issue, I sometimes get that around an edge of canvas when in reality it's solid. It could also be the image you're resizing doesn't have a solid, straight border, and when you enlarge it this is accentuated. Posting the original file would help.
Does this happen with all files? What method are you using to resize?