Why are some vents giving no heat, little heat, and a too much? Is there a way to control the amount per vent?

When the system was initially put together, there should be dampers located in the ducts. It might just look like a little lever.
These were adjuted for proper air balance. The further you are away the colder the air will be for heating and the warmer it will be for cooling. These can be professionally adjusted. Too much restriction will cause damage to the blower motor.

Hi, slekhraj!

Greetings and WELCOME to the site! I just moved your question that you had posted in Introductions to this topic area so that it would get the most exposure to those who are best able to answer it. Introductions is for people to introduce themselves and we try to not ask questions there.

I do note that you've already received a very fine response from KeepItSimpleStupid.

We would appreciate it if you would return to Introductions sometime to tell us a little about yourself though, if you would be willing to do that.

Thanks!