74-76 is probably good not sure what type of corys you have. If you are using a python you need to add water conditioner before adding the water and treat the entire tank volume, so in your case you will need to add enough water conditioner to treat 40g before filling with the python. With those numbers your at most a week out from being cycled provided you don't change all your filter media or do to much tank cleaning. I would leave the maintenance until after the tank is cycled and then do different maintenance at different times for a few months until its a little more matured. Just my opinion.Just tested my water, looks pretty good. Ammonia is 0-0.25ppm, Nitrite is 0ppm, and Nitrate is around 20ppm, maybe a bit less(or more..) My temp is 78F, and Ph is 7.4-7.6. I'll lower the temp to 74 due to my Cory cats, I just have it raised to help the bacteria. If using the python for water changes, it's safe to put tap water right into the tank as long as you dose for however much water you remove?