How many members/guests of the SDMB have posted within the last month?
How many members/guests of the SDMB have viewed a post within the last month?
I’m sure the mods can come up with more info, but the SDMB front page has a snippit at the bottom listing 6,721 active members in the last 60 days. I believe an active member for this purpose is someone who has logged in.
For what it’s worth, I know it doesn’t address your primary questions.
This was discussed in a thread I started last year.