Yes.
Yes, Slavonic was probably not the best example for this point, as it is a bit more complicated than the others. There are many complicated and boring reasons for giving Slavonic as an example here (similar to the reasons why historical linguists often throw everything old that isn’t Qur’anic Arabic into a “Classical” wastebasket category, even though they probably know that’s not right), but you are right that it is the one from that list of examples which would have never had native speakers to begin with. Так простите мне люди; я дурака.
Woah, hold on there, ܐܰܚܳܐ…we’re talking about different things here. The modern languages, yes, of course they’re alive (though quite endangered at this point; the reality of life in the diaspora does not bode well for their long-term survival).
Syriac is not alive, however.
Yes, and perhaps paradoxically, it seems to have improved a little bit as of late. When Tsiapera did her 1969 study, she listed the speakers as 1200 in Kormakiti (the other Maronites of Cyprus speak only Greek) and declining. Yet Borg, in his 1985 book on the dialect, bases his analysis on interviews and elicitations from CMA speakers in Nicosia (who hail from Kormakiti). He puts their numbers at 1300. That a population would grow by 100 in 16 years is not at all surprising or interesting. The implication that those 100 would grow up speaking the language or having it otherwise passed on to them is, though. If I remember correctly (I don’t have access to either book right now), the average age of the community is somewhere in the late 50s…