1. Does the order of conditions affect the result at all?

Conditions, I don't believe so, the ordering/placement of bindings though can effect the results a great deal.

When I say bindings, I mean something that involves a <-
 
2. The "," means AND or &&, right? So how do you write OR || instead? E.g
z<-[1..10] OR z<-[100..110].

For that scenario I'd just append the lists, z <- [1..10]++[100..110], if you wanted an or in conditions, you'd just use ||

 
Allthough I tried it, but it says isProduct and isSquer are not in Scope, so
I should define them first in WHERE-Clause right?

Yep, eg

listPairs = [...]
  where isSquare = ...
           isProduct = ... 
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Danny Gratzer