There is a simple binary answer.

1. If OP was unreasonably denied boarding, he due compensation for that under EC 261/2004.
2. If OP was unreasonably denied boarding, KL has a "duty of care" to reimburse (not compensate) for reasonable out of pocket expenses. This could be a meal, a hotel and the like, all depending on the circumstances.
3. If OP was unreasonably denied boarding, KL had a duty to rebook OP. Sounds as if it did.

I would make the claim for #1 and #2 under the Regulation. It will be for KL to prove that the denial was reasonable.

For the benefit of others, the assurance that both the e-ticket and reservation were in order gives me cold comfort. Allow a lot of extra time in this circumstance.