[mvp]

It is impossible to estimate accurately. I read somewhere which seem quite valid - "if we can't predict how much time was spent developing something even when we have the finished product at hand, what chance have we got of estimating something that is still up in the air".

About managing people, the best you can do in your situation if you really care is to inspire those you think are not performing as well as they could. Explain how working passionately will ultimately benefit them. Of course, treat them as human beings first and not as resources.

[waivej]

I'm not sure I agree with the estimating thing. Though I've only met one developer/manager that is good at estimating. He works at a steady pace and doesn't cave when people want things faster. It's tough at first but once you deliver on time, they respect your estimates.

He's also the only guy that I know that buys new cars with cash. He just puts away a "car payment" every month. When the old car wears out, he buys a new one.

It's tough to manage people that aren't pulling their weight. Take time to listen to what signals they are giving. If they want to work, help remove their obstacles. If not, do what you need to so the productive people don't get dragged down.