In case it helps I have looked up the figures of the 2 tanks with cherry shrimp in them and they are as follows,
Main tank PH7,, GH5, KH2, TDS 225 (mixed water)
Betta tank PH7.5, GH6, KH3, TDS 222 (tap water + mineraliser)
They are fairly similar to each other but neither is really in the 'IDEAL' recommendation range of CHERRY shrimp ,so it confirms that cherry shrimp are more adaptable and can thrive even outside those 'IDEAL' parameters? I suppose neither are that far out but it just shows there is a bit less necessity to get everything 100%, though if you aim for perfect you will probably get better results all round?
The usual GH range for Cherry shrimp is 6-8 and with the 1 part tap, 3 parts RO water mix you will be 50% there for G|H and just under 4 for KH! There are 2 products, one is GH+ and one is GH/KH+ so you need to get the right one for whichever route you plan to go, all RO water would be GH/KH+, mixed water would be GH+! IF you are planning the mixed route then that would be an easy adjustment you can do now by taking 25% water out and replacing with dechlorinated tap water, then adjust with the GH+ when you get it? This is the one I use, it is so simple as it is a liquid and even calculating is easy as each drop = +1gh (about 20ish TDS) / litre:
If you want to get this I have just done a dummy test on the website and you get delivery on it as long as it is one item, which is normal, but I thought you may need to pay as it is a bulky item to send?
The soil should have lots of what the plants need I would have thought and the poop from the snails/shrimp must be some fertiliser?
As JayC says you could leave the CO2 running for now as there are no shrimps, but I would probably turn it off and stop using fertiliser and just keep a close eye on the plants at this stage, after all you can start using them again IF the plants start looking unhealthy, but neither may be needed and it is better to know from the start and will make life easier long term. As I say I have never used either and my plants grow fantastic, in fact I wish they would grow slower, doh!
Ahhh ... the age old question of how to trigger your shrimp to breed. We will have to assume you have at least 1 male.
What are you feeding them?
Feed frozen bloodworms twice a week. The additional protein will give them more energy.
Add more Indian Almond Leaves (aka Cattapa leaves) to the tank to promote more tannins and biofilm.
Try raising temps to 23C or 74F.
A 10% water change might help the females moult.