Thanks God, I managed to sell 15% of my ardor before the dump.
Tomorrow people will massively deposit their ardor to bittrex and sell it (I think so)
Possible. But for now, the tendency is clearly bullish. The "dump" has almost been reverted and it's even possible that we'll approach a new ATH these days

Do they actually have a working explorer?
Yes, for now there are two:
https://ardor.tools - this one is already more mature and usable, but has a little drawback: it doesn't show child-chain (e.g. Ignis) balances if you check your account.
https://ardorportal.org - this one is more complete regarding child chains but also has some usability flaws still (so to see your account, you must append it to the URL:
https://ardorportal.org/accounts/account/YOUR_ACCOUNT)