100Gal Stocking Question

[Hsunami]

I have a 100 gallon with an FX5.

I am going to be receiving a shipment of about 40-45 rummies next week. And once my discus are a decent size i am going to be adding 6 into the 100gallon. Tank temp is running at 83-84

Would i be able to add some cories for bottom dwellers??

(Current stock)
30 ghost shrimps, 40ish red cherry
40 rummies (coming in this coming tuesday)
6 discus (will move from growout tank after grown)

If i wanted to add a few cories what kind and how many can i add?

And if i can't how many rummies do i need to lower so i can add about 6-8 cories? I plan to do about 30% wc weekly.

Tank only has patches of Java moss and nothing else.

[Northwoods Discus]

I would monitor your ammonia, nitrites and nitrates as you increase your fish load. 30% water change once weekly may not be enough. It may take longer in a large tank for nitrogen build up but once it does changing only 30% weekly will not lower it much.
Others can chime in but just because a tank is large does not lower the percentage change needed. Eventually the nitrogen waste builds up. Monitoring it should give you the answer. If your nitrogen levels stay under control than you are changing enough water. Plants may take out some nitrogen, as plant matter decays the nitrogen will be released. Removing excess plants should remove some of the nitrogen. You need to account for other minerals etc lost with plant growth hence more water. I think every tank setup is different on the needs. You have planned well with growing out your fish in another tank. 40 plus schooling fish will look good.