Yes. Blynk IoT doesn’t use energy.
You should have received an email giving you a 50% discount on the first year’s subscription to a Plus or Pro subscription…
Yes that’s an option. I think its done in the Billing section of the web console.
No, that’s not an option.
You’d need to check if the NodeJS library has been updates to be compatible with Blynk IoT.
Personally, I don’t think the RPI makes a good platform for Blynk projects. You’re much better off with a NodeMCU or ESP32 and C++