adding passive EQ between PA450UM and PAD5000.5

I'm going to add a passive EQ between the Polk PA450UM Tuner/Amp module (which functions as a pre-amp in this application) and the PAD5000.5 Amp in a marine application. The 450UM has RCA outputs for FR, FL, RR, RL, (no dedicated Sub outputs) and the PAD5000.5 has corresponding RCA inputs, so that setup is very straight forward and how it came wired from the factory. The EQ I want to install in between the Amp module and the Amp has just one stereo input (R+L RCA inputs). Can I use either the Front or Rear outputs from the 450UM for the input to the EQ? If yes, which is better, or no difference? I'm thinking yes, and no difference.
Also, the Amp has 2 inputs for Subs, labeled as Sub 1 and Sub 2, not L and R, and both inputs are single RCA. The EQ has a Sub output (L+R RCA) in addition to FR, FL, RR, RL. Can I use the L+R Sub outputs from the EQ into the 1+2 Sub inputs on the Amp and get both L+R channels through the Sub? In other words, will 1+2 (as labeled) function as L+R for the Sub? Thanks very much, as I'm new to this forum.