Just wondering if the verada blackout cluster fits and plugs into a tl magna manual without any modifications?

The KL/W one will as it uses the same plug. Earlier (KJ1 and previous) will not.

Thought that was the case, was looking at a kh cluster.. So if I buy a kl-kw one the auto cluster will plug straight into my manual?

correct.

Yes it will, but you'll obviously lose the gear selector display. Just put a piece of black tape over it to "remove" it - you won't notice the tape there, it'll just look black.

KH and KJ1 use different upper dash looms to the KJ2 and later models. Also, TJ1 and prior Magna models use a different upper loom to their Verada counterparts, but in your case TJ2/KJ2 and later use the same looms so, as 380Mitsu said, it will plug straight in no problems.