From my latest experience with PokerStars and ACR/BCP (where I play):
$100 daily (Platinum)≈230 @ PS
≈140 @ ACR/BCP
PS $300 weekend (Platinum): ≈300 players
$100 weekly (Silver+Platinum)≈350 @ PS (Friday)
≈180 @ ACR/BCP (Sunday)
$100 Saturday (Bronze+Silver+Platinum)>3000 @ PS
=300 (cap) @ ACR/BCP
The system will reward you with Silver level after you reach 25 total posts. When you lose Silver, you can't reach the 25 total again, because you've accumulated more posts than that. It's a one time only gift for your first 25 posts (not for every 25 posts you make). If you keep a good activity for 30 days, you can get Platinum level now, since you are past 75.
BWT, weren't you Platinum when you dropped to Bronze for inactivity? I thought that Silver alone can't be lost for inactivity.