Is there for example a Gemini search engine?
Yes. Two, actually (that I know of).
- gemini://tlgs.one
- gemini://kennedy.gemi.dev
Will FF display a Gemini page as text only?
Firefox doesn't directly support Gemini, but you can view pages through a proxy like portal.mozz.us. Gemtext, the standard page format, has basic formatting syntax, and yes, it's text only. There's no mechanism for embedding images in pages - the best you can do is just link to them. In this one popular client, Lagrange, clicking on a link to an image displays it under that link, but other clients handle image links differently.
Where do you hang out and exchange links 😁 ?
I just lurk and read gemlogs (of course they can't be called blogs, that's short for web log!). There are sites with feeds of latest gemlog posts, and many sites that offer Gemini hosting have a list of recently updated pages. There are some minimal social networks, too. The front page of portal.mozz.us has a few links to these kinds of spots.