International website - SEO domain setup

Hello,

I have read Google guidelines regarding international SEO domain setup.

What they recommend is one of the following options:
a) country specific domains - domain.en | domain.de
b) subdomains, aka en.domain.com | de.domain.com
c) folders, aka domain.com/de | domain.com/en
d) url parameters, aka site.com?loc=en | site.com?loc=de

My question is - are there any other options, which WOULD NOT change the way the URL looks like?

We have a website which is aimed at people from various countries.

What we want to achieve is:
1) someone searches for phrase in google
2) he sees indexed LOCAL version of the site, which is based on his browser data (for example, en-en.domain.com)
3) he clicks and is redirected to the main domain - domain.com BUT content of the website is still in English (in this example)
4) When he chooses to change language of the site in site settings, URL REMAINS THE SAME - domain.com, BUT language changes to whichever he chose.

Is it possible to achieve so that it does not hurt SEO rankings? Facebook does similar things, but from what I have heard from SEO specialists - "FB doesn't need to worry about SEO, they have a deal with Google"

Simply put - are there any other options when it comes to international SEO apart from those listed above, which would allow URL to stay the same even when changing language of website?

I will be grateful for your answers - if you worked on international projects and know about this stuff, I am willing to pay for consultations if needed.

Best,
Robert

 

I have one additional question - is it possible to display different metatags for single URL (title, description - basically what user sees in SERP) based on user's language settings in Google?

If so, how can it be done and does it influence rankings in a negative way?

Best,
Robert