What does it mean to say 30,000 monthly credits and 1500 daily refresh credits? If my project takes 7000 credits (the way your demo does) then does that mean I couldn’t actually do it on the lowest available pricing plan because I couldn’t use 7000 credits in one run? If this is the case, what am abysmal pricing model!

The daily refresh isn't a cap on usage, it's additional credits you get each day (resets to 1,500 nightly regardless of use).

You can use your full 30k balance in a single run if needed. The daily refresh just tops you back up over time so you're not waiting for a monthly reset.