Do the enhanced editions include the original ones?

Yes you can unlock the originals when you purchase EEs.

How, please, I'm trough the options, and when I want to install, the only 'option' is to create a shortcut on desktop.

You have to first Redeem and then download the original installers.

The redeem code should be on your GOG account page. DO NOT USE GALAXY. On a browser (such as Chrome or Firefox),

go to your account

find Baldur's Gate EE (or EE2). Click it.

And then click MORE>> Serial keys.

Here you'll see something like http://www.gog.com/redeem/.xxxxx... You can use that link to directly redeem the original.

Of course, after redeeming the original, you have to download and install it.

Also note that, like all GOG gift codes, redeeming these requires solving a frequently impossible Google reCAPTCHA. If you can't get past the captcha, try contacting support. They won't help you, but they need to know how horrible their captcha mechanism is.

Usually the interface surrounding the Captcha was designed to be used without one, and the Captcha is just slapped on somewhere there is free space for it. That means there's no instruction to tell you what things should be accomplished on the page first. This often leads the user to attempt to go forward to a spot that checks for completion of the captcha when the captcha hasn't been completed - failure. This is a pet peeve of mine.

This one is so much worse than that. If you have not unblocked the relevant Google script (which is hotlinked from an unrelated domain, so it's blocked by default on any browser that disallows unexpected third-party domains), then you get a page which states Please complete the Captcha to continue. It's nothing personal, just a crippling fear of robots., but there is no sign of a captcha at all, nor any hint of what to unblock to allow it to appear. If you unblock the Google script, it still won't work, because that script is just a loader for another Google script. Several layers down, you will finally get the script that actually adds the captcha to the page. Even if you get that far, there is a decent chance that when you solve it, the solution won't be accepted. The server just returns a generic error and tells you to try again - forever. Support refuses to accept that this is user hostile, or that the design could be better in any way. They think it's perfect as-is. As a result, I never buy GOG gift codes, because I know the people to whom I would give them would be unable to redeem them, so it would be money wasted.