VHDL- counter problems
I've taken the liberty of cleaning up your listing and formatting it for compactness and readability, so I've undoubtedly messed up the line numbering.

The specific errors you're getting are caused by the fact that you can't do arithmetic on std_logic_vector, e.g., to increment and decrement your counters. At a minimum, you need to include the library ieee.numeric_std in order to allow this. See the answers to this question for additional details.