Can spotify give me suggestions? Like if I can think of 7 songs, will it fill the gaps?
Yep! You make a playlist, right click on it (or ctrl+click if you're on a mac) and then choose "Start Playlist Radio". Then it uses your playlist as a Pandora-like station, but it will mix in the songs from your playlist as well. While you're listening, you can just drag the current song or recently played songs to your playlist. It's totally awesome.
Compared to Pandora it gives you more control but it doesn't do quite as good a job thinking outside the box.
It costs $9.99/month (plus data charges unless you're on wifi or you sync the playlist) to use Spotify mobile. If you pay for it you also get to use it in "offline mode" meaning that you can tell Spotify to sync a playlist to your phone and then it can play it even without burning up your data plan or if the connection is bad. Pandora is free on your phone (not counting data charges) which is the big plus for Pandora.
I still buy mp3s and copy them to my phone to use as music for the car, the gym, and travel.
I don't know of Spotify runs on SmartTVs or fancy DVD players. I would google "Spotify Toshiba BD-X701" or whatever the model of your Smart TV/DVD player is. You might get some hints. There may be something a version of Spotify for PS3 or Xbox eventually, but it's not sure.
Oh, one more thing ... spotify is smart enough to know your music collection on your desktop. I don't know if it lets you play that collection on other devices without copying.
Can you sign up for spotify without facebook? I can't see how. If you can, someone please direct me.
Not anymore. When it first opened in the US you could but in exchange for the "post to facebook" stuff FB forced them (and Rdio) to use only Facebook IDs as logins. It's awful.