As a possible explanation to some of your comments, Cubboo, maybe these will make sense:
For the $15 minimum in offers before one can cash out - I figure it's to encourage members to remain active on FC, as it's the membership that helps make them (FC) as well as ourselves money. Other sites that don't have that may end up with members who are great at referring members who could make the minimum payout based solely on referrals, but don't work the site themselves anymore (because they don't need to with their recruiting efforts). Based on the referral bonus structure in place at FC, by requiring a minimum amount each person needs to earn for themselves before they cash out ensures people keep working the site to be paid their full referral bonuses. I see this as a benefit as a good recruiter may get a lot of the $1 and $2 bonuses for people signing up and completing one offer - but unless those referrals continue to work (so you can get that $5 bonus), FC may ultimately lose money.
I see this as one of the benefits of FC over other sites as it generates more loyalty for the site. As you've probably seen, many of the long time members are very passionate about FC, and this may be one of the key reasons why. Plus, I see it as a benefit for nurturing referrals - if "you" are knowledgeable about the site from working it, then you'll be able to better assist your referrals, thus helping them make more money, which makes more money for you, and ultimately FC too - win all around.
For the $3 bonus - just a little patience is needed here. Only the first bonus is the longest wait, but if you are regularly participating and meet the bonus requirements each month, then it should be a pretty steady $3 per month once it gets going. Also, even though FC verifies the posts in house, some considerations is (a) how big is the FC staff - may not have many people devoted to reviewing posts, and (b) consider how many people are posting on this site - even though it may appear to be an easy task, the Admin has indicated in posts I've read in the past that FC really does very all posts before granting the bonus - and there are probably some people who've not received a bonus due to having some of their posts "rejected" by the reviewers.
Over time, I've seen the staff activity come and go in waves - I admit the activity has been a bit lighter than usual recently, but there could be many reasons for that - under staffed, working on new features which is taking priorities, vacations, unexpected happenings - who knows. Again, I'd recommend just being patient. Even if they answer later than one would hope, they do eventually answer.
For the offers - in addition to the offers on the main page, the surveys, videos, human tasks on the "Daily" page are also considered offers too, and those tend to change up with faster frequency than the main page. I like your idea of adding something like an "offer of the day" - where a new offer is introduced. I think that might be a fun addition. Probably the hardest thing there would be FC finding enough offers to do such a thing on a daily basis - maybe they can start weekly. Maybe if you've seen offers on other sites, you can post some suggestions in the "Suggestions" forum.
Hope some of my perceptions on the items give you a different perspective or different way to think about them. I'd recommend you add your "offer of the day" idea in the suggestions forum. Nice idea!