What will be Heroku Hobby Dyno Plan Usage with node-schedule module?

Question

The code below is gonna send an email once in a minute to the people listed in the queue. I couldn't decide, which plan to use to work this code in Heroku. I see that, the free plan goes sleeping, but I somehow can manage to sort the problem out by using kaffein.

const schedule = require('node-schedule');

const job = schedule.scheduleJob('* * * * *', function(){
  console.log('The answer to life, the universe, and everything!');
});

1. I want to know that what the cost of heroku will be, if I were to run the code above?
2. Which plan should I choose for this code with minimum cost?
3. How much dyno hours will it cost with this code?
4. I found out that another way to do this is to use Heroku Scheduler. if I use it, will it cost me any extra fee other than free and hobby plans?