what is the prefered option of arithmetic operations using logic vectors and constant? convert logic vector to integer and do the operation or to convert the constant to logic vector? I have samples from A/D as logic vectors with some resolution and constants. I want to do arithmetic operations between them according to formula? if anyone has examples of such thing it will be very helpfull (VHDL).

Never ever do an arithmetic calculation on a unconstrained vector. For calculating you have signed, unsigned and integer data types. Why? When calculating with std_logic_vectors you cannot determine whether its an unsigned or a signed operation. And if you simply copy the few lines with the calculation you discard this information.