[RPG] What does the percent after spell-like ability mean

Stat Changes

It seems very clear that you apply no stat changes.

This ability functions as a polymorph spell, the type of which is listed in the creature's description, but the creature does not adjust its ability scores (although it gains any other abilities of the creature it mimics).

There are no qualifiers here -- it says the creature does not adjust its ability scores, so it doesn't! The part of polymorph that you're looking at says that you

adjust its ability scores to one of these two sizes using the following table

This is exactly what the change self ability tells you to ignore.

Even though it doesn't use the word "adjustment" in the actual text of alter self, the word would generally mean any change to your stats. (And it would be a bit weird if shifting into a smaller form increased the strength of a Titan.)

Other abilities

There's nothing here to modify how polymorph spells work:

While under the effects of a polymorph spell, you lose all extraordinary and supernatural abilities that depend on your original form

Note the qualifier. You only lose the ability if it was contingent on your original form. In many places the DM will have to make a judgement call on whether that applies. But obviously, say, a manticore that shifts into human form can no longer use its Spikes special ability. The rule is intended to rule out nonsensical situations, so the change shape ability doesn't alter these rules at all.

Your DM is correct: it does provoke an AoO.

The confusion here comes from your reading of the sentence where you believe that the second part only applies if the first is true. The sentence is in fact a two item list; the first half and second half do not interact with each other in any way.

The d20pfsrd also says

A spell-like ability has a casting time of 1 standard action unless noted otherwise in the ability or spell description. In all other ways, a spell-like ability functions just like a spell.

And spells provoke (except when cast as a swift action).

Interesting, you can Arcane Bloodrage defensively, since you have not actually entered a bloodrage when you apply the effect, it is done as part of the activation.

This is the RAW on the matter. The fact that swift action spells do not provoke does not mean that free action spells or spell-likes do not, though it is certainly worth making that point when discussing this with your DM. (Especially since the reason is that there are no free action spells any more is, to the best of my knowledge, because when pathfinder came out it had turned them all into swift actions)