‘localhost’ references on live site

Some problems with ‘localhost’ being used on the live site.

I developed a website locally (xampp, wordpress). I used localhost in the site settings, because I had to, and all worked fine on my PC.

Then I transferred the site to a server and things were broken in multiple places.

1) The images in the Pages articles were hardlinked to localhost.
Like this: ‘http://localhost/wp-content/…’

I would be expecting them to be abstract like this: ‘wp-content/…’ ?
How do I fix that? (I had to go to each image and fix it separately)

2) I could not navigate the live website or even login to the control panel, because all links pointed to localhost. I had to do some trial+error behind the scenes stuff to finally get it to work.

What would be a simple way to do this? Being able to easily move sites back+forth is important for me.

Thanks!