I guess in that last category sports are commonplace, but it’s more “I’m training for a marathon next month” or “you should come bouldering sometime” rather than following professional sports on tv.
Yes and no. If you HAVE to choose a specific hobby, football will have more chances than others; but it will still work in a minority of cases and assuming carries an implication.
A comparison I could make is starting a conversation in the US with 'did you watch fox news yesterday?'. Out of all channels, it's the most watched one; but you still have high chances of asking a non-viewer, and then get hit by negative connotations.
Personal hobbies are much better topic for various reasons (you don't assume, people will naturally be exited about discussing their own, etc).
Sports and cars is more common with the older generation, but anyone below 35 will probably be uninterested, unless your circle is finance or blue collar work.