1: Not correct
2: Correct
I've always used this to monitor /pop on the different servers. If we take those figures at face value, then a comparison with Steam charts shows, that 80-85% log in using Steam. This figure used to be around 90%, but I believe the decline in steam user percentage is a result of Nekrova being included in the above link. My guess is that less of the old Innova players (Innova was never tracked) who migrated to Nekrova (which is being tracked) use Steam than Citadel and Jericho players. So saying that Steam charts only show a small portion of the player base is not correct. But they are not entirely accurate either.
Related to Jericho, the past week shows the following daily peak /pop:
Around 230 players on weekdays
Around 260 players during the weekend
Considering those are peak numbers, then @Darkzero3802was quite close with his in-game popservations (ayyyyyy!!!!).