Need to speed up import times on Lightroom Classic - 125,000 photos over 11 days

Here are my specs:

(Photo Editing PC) - Processor: Intel (R) Xeon(R) W-2123 CPU @ 3.60 GHz RAM: 64GB GPU: Nvidia GeForce RTX 3060 OS: Windows 10 Pro Editing Software: Lightroom Classic 13.3.1

(Photo Ingesting PC) - Processor: 13 Gen Intel(R) Core(TM) i7-13700 2.10 GHz RAM: 16GB GPU: Intel(R) UHD Graphics 770 OS: Windows 10 Pro Photo Organizing Software: Photo Mechanic

Both computers save almost all data (Lrc Catalog is on Photo comp's internal storage) to the company's network drive. This cannot be changed due to liability of files/storage devices becoming corrupt and lost. 

Okay, so a quick summary of my position. I've run the photography department of a festival for three years, we have 8 hired photographers with a variety of different cameras to capture events over the 11 days of the festival, ending up with about 125,000 photos ingested and tagged by festival end. Over the past 2 years the ingesting has gotten slower abd slower, which slows down my editing/tagging process. The IT Department gave me a second PC (ingest only), so I can ingest on the Ingest PC and edit on the Photo Editing PC at the same time. For example, my camera takes 30MB photos, the hired photogs' cameras take images up to 90MB. Today, I tried ingesting about 1100 photos (30MB each) and it took 25 minutes to get them ingested and cataloged. I'm trying to figure out if there are any ways for the ingesting to be sped up? Below I have written out my process for ingesting. Below that are some questions that I hope to get answered.

The process I hope to use for the 11 days is: Plug card into reader and into Ingest PC, I'll hopefully get approved to use Photo Mechanic to tag and add metadata to the photos for each photog, then I will ingest the photos into the RAW folder on the Network Drive, (while this is all happening I can still edit/tag photos from the previous day on the Photo PC (ideally)), once all 8 photogs have had all their cards ingested (approx 12,000 photos each day) and I am clocking out for the day, I will start importing (Add) the photos to the lightroom catalog and keep them in the same folder as before, hopefully this will be done before the next day begins.

I need speed and consitency on my side, so here are some questions!

Does Photo Mechanic (PM) Metadata carry over to Lrc? If I add tags on PM as well, will that carry over?

Is it possible to ingest multiple folders with one import? Like can I select all of the photos from all the photogs from a single day an import them all at the same time? As to allow the import to take place over night?

Does Nikon, Canon, and Sony imported photos show in-camera ratings? I know my Nikon Z6 registers the in-camera ratings, but I'm unsure if that should follow through with the other cameras.

Any other tips for speeding up ingest times? Having previews being made help with the quick tagging, so I typically need them.

Thank you all for the help in advance.