I have a question on how the trolls free dermal armor works, it shows +1 body after the racial modier for body (+5) on the table under character creation. Now does this mean that they get the +5 and then an additional +1 for having the dermal armor, or is the dermal armors modifier already calculated into the +5?

And how would upgrading to a dermal 2 or 3 work for a troll, would they have to get their natural stuff removed or can they stack implanted dermal with their natural one?

The general consensus is that, first off, the dermal armor is after racial modifiers, so a troll with initial Body of 3 would possess Body 8(9) after racial modifiers and dermal armor are factored in. As far as compatibility, I believe that it is compatible and cumulative with any form of augmentation, even orthoskin and dermal sheathing, which are incompatible with cybernetic dermal plating.

The troll combat mage was one of the examples of character creation, and they gave him a Body of 6 (1 point plus the 5 point racial bonus) - on his sheet, it is listed as 6 (7). The mercenary and sprawl ganger both have Body-increasing cyberware (bone lacing and dermal plating, respectively), and in both cases it is cumulative with their "natural" dermal armor.

So by the rules, Wireknight is right on both counts.

remember, Troll Dermal Armor is considered augmentation. It give a dice to damage resistance but there are cases that require an unaugmented body test. Chemicals and pathogens come to mind. Dermal armor adds nothing to an unaugmented bod test, naturally.

Don't healing checks also use unaugmented body?

That is correct. The Dermal Armor (natural and artifical) help against Poisons and Toxins that have a contact-vector or injection-vector.