Regarding "1.": no, according to Wikipedia, which cites a CRS report for this info:
Every person elected speaker, however, has been a member.
The report itself says, in slightly more detail:
In the 1997, 2013, 2015 (both instances), 2019, and 2021 elections, votes were cast for candidates who were not then Members of the House, including, in the initial 2015 election, the 2019 election, and the 2021 election, sitting Senators. Although the Constitution does not so require, the Speaker has always been a Member of the House.
So, until 1997 there weren't even any votes for outsiders, it seems. The report only covers elections since 1913 though.
It's hard to say how real the prospect is (in the article you linked Trump has equivocated about it), but some Democrats appear to want to counter the possibility by passing a law.
Rep. Brendan Boyle (D-Pa.) introduced the MEMBERS Act – which stands for Mandating that being an Elected Member Be an Essential Requirement for Speakership – which, as its name suggests, requires House membership as a prerequisite for becoming speaker.
Boyle specifically cited the speculation about Trump as the motivation for the bill, calling it an “alarm bell” that the current requirements should be changed “in the name of protecting our nation and our democracy.”