After switching about 3 years ago, I tried running photoshop through wine. It was a little glitchy visually (I hear it's ok nowadays though) so I tried gimp and just couldn't get used to it. I tried krita and its perfect for what I use it for, very easy to use coming from photoshop. I'm not sure about actions as I don't think I used them in Photoshop but it has plugins so you might be able to find something to replace what you used before