My question is while playng the cannoness does skill tests AND battle rolls explode on 5 and 6? or skill tests only? I was under the impression that battle rolls are a type of skill test.

Battle rolls pertain only to resolving combat with monsters, whilst skill tests are of the type Test Attribute X(with x being the target number you need to reach to pass the test)

For instance, if you're required to pass Willpower 14(like in the Garden of Nurgle in the Inner Tier), you need to roll high enough to reach or exceed 14.

Your skill score is comprised of current tested Attribute value+die roll

Whenever the Cannoness rolls for skill tests, her dice explode on both 5s and 6s.

Cannoness' battle rolls do not explode on 5s!

Also, note that rolling a 1 on a skill test(before explosion) results in automatic failure regardless of score.

Not so with battle rolls.