Engineering team grants hull resist
Science team grants shield resist
Various eng consoles can grant various resists
One of the new skills coming grants resists

How do all these resist options work together? do they stack? or multiplicative? Is there a cap on maximum resists ( I assume so but cant find it documented anywhere)?

Most "resists" apply only to your hull. Resistance values are additive, but are subject to diminishing returns. For example, I can use Hazard Emitters, Engineering Team, and Brace for Impact for a total Kinetic resistance of 107% or so, but after diminishing returns, this turns into 49.5%.

The damage resistance to shields that comes from abilities such as Emergency Power to Shields and Science Team works only on damage taken to your shields. I haven't done any testing to know if those are subject to diminishing returns, but since there are far fewer abilities that provide such a benefit, they might not be.

Resists work differntly than they sound.
lets say you have 100% resist, that doesn't mean you will resist 100%of the damage, its means basically it takes twice the damage to kill you than it normally would.

well thats the way i read about it on here somewhere.

Yes, that's correct. The resist bonuses don't actually diminish, in the sense that they linearly add to your survival time against that damage type. They look like diminishing returns when calculated into an absorption percentage number, which is what is displayed in your ship's stats readout.