If i bridge my 2 subs, does it split the max RMS between the two?

ex- 600w RMS mono push out 300 to each sub?

also, if i bridge the two subs together, does it lower the ohms?

ex- two 4ohm subs bridged turns into 2ohms

yes and yes

You don't bridge subs. Bridging is an amplifier function. Subs get connected in series, parallel or a combination of the two called series/parallel.

Two 4ohm subs in parallel = 2ohms
Two 4ohm subs in series = 8ohms

As long as both subs have the same impedance each will receive the same amount of power. So if the amp delivers 600W then each sub will get 300W. If one sub is 4ohms and the other is 8ohms then the 4ohm sub will get 2/3 of the power and the 8ohm sub would get the other third.