Eclipse and complexity

Dear All,

we use ECLIPSE to solve equations with  constraints on integer and 
boolean variables,
exploiting the /ic/ library.
An example of the implemented equations is:

X1 :: -67108864..67108863 , X2 :: -67108864..67108863 , X3 :: 0..1, 
(neg(X1 #= 5)) and (X1 #< X2) and (neg(X3 #= 0)) ,

So, that is the complexity for the algorithm applied by the
solver to get a solution for the equation?
And the complexity to get the list of all possible solutions?
Moreover, the complexity to get a random solutions  (i.e. with the
statements indomain(X1, random), indomain(X2, random) is
the same of getting the first available solution (i.e. with 
indomain(X1), indomain(X2) ) ?

However is there in a better solver that we can adopt to solve our 
problems?

Thanks for your attention,

Cristina