Problem migrating to other server, absolute image paths with twenty eleven theme

I’m developing a site with WP on https://localhost/sitename.com.

When I upload my site online, in another hosted server, I get the problem that every path retains https://localhost/sitename.com as root and not https://sitename.com.

I understand there are three levels of problems:

1. The first, easy to fix, is to change the path in the admin settings. That fixed the menu links.
2. The other problem is within the images. I’ve found no other way than doing a *very unelegant* database search and replace with a plugin. That sucksa and I have to do it everytime I update the database from the local server.
3. Last problem, NOT addressed by the plugin, is the “twenty eleven” theme: every header has its URL hardcoded in some JSON-like data structures in the db! I change the URL manually in the database and still doesn’t work, have to reassign the image manually from admin!

This is so frustrating, how come that such a wonderful piece of software uses ABSOLUTHE PATHS (unlike, for example, a CMS starting with J****)? Any shortcut to speed up updating my live online site? Any help would be really appreciated, thanks to you all.