Ah you are on your way to the most challenging aspect! Lets see if we can get you going...

First, pretty sure I need to have the CSM perform a plane change before the LM lifts off, but not sure how to get that info from the RTCC. Is this a General Purpose Maneuver? Or do I play with the LOI processor somehow? Also, what about the REFSMMAT? Do we use a P30 REFSMMAT here?

Yeah you will see the plane change on the flight plan as well. Which gives you a good idea of the target time. You will be using the descent processor with the new RLS here so first update your RLS (Utilities->landing site, select target as the LM and hit CLC).

Then move to the descent processor and select the CSM Prelaunch Plane Change with the MOD button. Use the TIG-1h as TH1 and your predicted liftoff time as TH2 (you can use the flight plan for this for now.)

You then calculate the burn as you have with others in the RTCC and after you can generate a P30 REFSMMAT heads up.

Second, looking at the RTCC Input Reference Guide for the ascent, I've gone through this a few times but it seems to me I'm missing the big picture. There's a sequence of events that's unclear to me. For instance, it looks like I need to know my lift off time to begin using the Lunar Ascent Processor. But where do I get that? The CSM's orbit is going to dictate that, so until I complete the plane change will these different processors (LLW, LLT) generate any solutions? And am I looking at the "T3, Ascent (Concentric)" section, the "Direct Ascent & Tweak" section, or both? Lots of questions and I don't know where to begin.

You can, if you wish, put the CSM plane change into the MPT and then proceed to compute your ascent before you burn it if you wish, or you can burn PC and then compute the ascent without the MPT, your call but I encourage the MPT so you can get other data.

In any case, since you are running a direct ascent profile (Apollo 14+), you will be using the Lunar Launch Targeting Table (LLT) to compute the ascent. You will need to do some "working backwards" timings here.

First, you need to compute your expected TPI time. This is going to be sunrise -16 minutes on the orbit after lift off. I use the SR/SS table (MSK 1502) to find that orbit's sunrise and then subtract 16 minutes for my TPI time.

You then can use the LLT, set your target to your CSM, TTH to your estimated liftoff time (you can use what you used for the CSM plane change here), and your DT (time from insertion to TPI) to 45 minutes, and RDO to 32 fps. Then try calculating a solution.

Next we do a little iteration to fine tune the actual liftoff time, you will go back to the ascent processor and CLC, this should give you a slightly different TIG, and then back to the LLT and CLC again. Here you want to make sure your TPI time didnt change on the LLT page, if it has, adjust your DT to get your TPI time you computed previously. Do this a few times until your liftoff time and TPI time remains constant. I would encourage writing the liftoff and TPI times down for reference as well at this point.

Then we want to determine the insertion time. You use the checkout monitor with your ascent maneuver on the MPT here and you can get your insertion time (should be the GET in the top left) which you need for the tweak burn.

Since you cannot compute the dV's yet, we will just get the table ready to compute quickly since the tweak is just a few minutes after insertion. TAR->REN->TI->OPT->Both Fixed. Set T1 to your insertion time +3 minutes, and set T2 as your computed TPI time. Then set up the parameters OFF: P51,15,1.7,26.6,130;

Before disabling the MPT, you can use the plane change and ascent you have on there to uplink time tagged state vectors per the flight plan. After, make sure the MPT is inactive after this. You should then be able to compute the ascent pad, have the updated tig for the alignment and P12.

After insertion you quickly will compute the tweak burn with the following: TAR->REN->TI->DIS->CLC->MPT->CLC, read tweak-burn DV’s which you will burn with a V47 at your cutoff attitude.

I know this was a lot, so if you have specific questions within let us know!