You have some complicated routing, but you are not too far off. I had to put on my readers and sketch out what you have and what you would like. Just to reiterate, your OUTPUT SLOT is setup with Buss1/DIR1 to Buss32/DIR32 going out of the DM over FW CHs 1-32. Fine. We may make a slight change here, not sure yet.
Let me first address your volume or "no sound" issue (near the end of your inquiry).
Whenever you are assigning stuff to your Busses, and you are monitoring out of the STEREO outs, like for CR out (Control Room) or the XLR stereo outs, you have to go to your BUSS layers and turn all faders up to 0db, (Unity gain). Now you have to individually assign those Buss channels out through the STEREO outputs, so you can hear them through your monitors (assuming you monitor through the STEREO Buss outs). To do this, go to your Buss layer, find the channel you want to hear (maybe all of them in your case) and hit SEL. Now, find the STEREO button near the top of the Output Assign section, next to your fat channel area and light it up. This will assign that Buss channel to the stereo buss so you can hear it. Adjust your STEREO buss fader as necessary for XLR out control, or set it to 0db and adjust your CR pot for the 1/4" out Control Room volume control. OK, Moving on....
Mixing OTB, you would like to send each track back into ProTools (Post DM Effects I presume?) You are pretty much already there. You will have to make a new track in ProTools for every Post effected DM channel you want to record. You say you have 11 mono tracks and 2 stereo tracks. That's fine. Just make 11 new mono tracks and 2 Stereo Tracks in ProTools. For each track select an input from your FW to record, associated with the corresponding DM Buss/DIR channel output. Since you already have your DM outs set to Buss channels, your effects will go out with each channel over FW back into ProTools. When you feel like the mix sounds good on the DM, arm the tracks in ProTools and record away. Just make sure your gain structure is correct through the board and that you are not also listening to the STEREO buss from ProTools by mistake. (BTDT)
Next, you want your vocals mixed to a two track Buss and all your music mixed to a two track buss. That's fine, but it will negate everything we just did. Nonetheless, that's easy to do and it sounds like you already have part of it done. At least the vocal part. Just do the same for all the music parts. You have your vocals assigned to Buss 1-2, so just assign all the ProTools output tracks to Buss 3-4. Remember to adjust the buss faders to unity and assign each buss track to your STEREO buss, and adjust your STEREO fader as necessary so you can hear them. (assuming you monitor off of your STEREO buss.)
Now, you said that you have Buss 1-2 mixed back into the board inputs at channels 17-18? Because you have them assigned to CHs 17-18 out of the FW? I think this may be unnecessary. You may be messing with your gain structure here. If they are too quiet, it may be because you don't have the buss faders up to 0db, or the buss outputs assigned to STEREO. Check this structure, and, if it works, forget assigning those buss tracks back to 17-18.
I think that covers it so far. Really double check your monitor routing as described. Good luck