I pretty early on cottoned on to the theme --- a fairly complex one where part of an answer must be read in a "circle" of four squares looping back to the above row, backwards, then down and re-using the letters from before to complete the phrase. The first one I got was BEVERAGE ROOM (reads as BEVEROOM), which made UNDER ONE ROOF (reads as UNDEROOF) fall into place because I was already thinking that had to be the answer to "all together, as a family" even though it didn't fit.
- Update: the loops all start with ER. SupER LoopER! I didn't even notice that.
Never heard of the painting "The Hallucinogenic Toreador," but I knew with a title like that it had to be DALI.
South American plains" are LLANOS? What happened to *PAMPAS?
Look, if I don't know anything at all about baseball or football, how am I supposed to have heard of ESA Tikkanen? Also Karen ENKE. I'll try to remember you guys, but it's probably a lost cause. See you in a future puzzle.
The SULU Sea lies within the Philippines, between Borneo and Visayas. Fun fact: The "Star Trek" character Mr. Sulu was named for the Sulu Sea.
Woamn "who swam the English Channel in 1926:" Gertrude EDERLE. She was 21 when she did that. She wasn't very elderly! Ha? Ederle. Hm.
"Altar constellation:" ARA. Never heard of it. Fun fact: In ancient Greek mythology, Ara was identified as the altar where the gods first made offerings and formed an alliance before defeating the Titans.
In all, I loved this puzzle. The things I didn't know were still eminently guessable. (What other Roman philosopher is there besides SENECA? Who would Homer exchange cross words with but LISA? I may not know who Mahmoud Abbas is, but it sounds like he may be the head of the PLO. Etc.)