Help with Featured Posts, Recommended Reading, and Pin it Button

Help please!

I recently switched to a different wordpress theme and I’ve having some issues with the new theme. One, there’s a featured post slider at the top. For now, it only shows my most recent posts. I would like to select what posts slide in the header. How could I code for that?

Next, at the bottom of each posts there are social media share buttons. The pin it button has replaced my pinterest button. How can I fix this?

Last, I have recommended posts to read at the bottom of each post. How may I code it so that the images are the same height AND width, regardless of the landscape? I recognize this will probably cut vertical images into horizontal, but that is what I want.