You can connect as many apps & scripts as you want to our endpoints. You can connect your bots, scripts, automation, etc. We don't have a hard cap in place for max connections so it would be best if you kept an eye on the API Credits you're using, please test and adjust accordingly.
You can view our pricing plans here https://www.quicknode.com/pricing. We have a calculator in place in the form of a slider to give you an idea of how your billing will look like