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Exactly this, on both points.
Find out the minimum repayment amount (probably 5%, as @Soul says) and pay this off in month one. Divide the remainder by 23 then set up the direct debit to pay off this amount for 23 months.
Also, I'm not sure how they calculate 24 months. For example, if it was issued on 1st Dec 2015, do you get 0% interest until 1st Dec 2017? Your first bill will most likely arrive on 1st Jan, with a due date of 1st Feb, so your 24 monthly payments will exceed the 24 month 0% interest period, maybe. Worth investigating.
Is the amount you're paying a % of the total or a set amount which is 4.17% of the total now?
If it's an ongoing 4.17% you'll be paying a diminishing amount each month rather than paying it off as calculated.
Also, be aware that most credit cards require a minimum payment which is usually 5% of the outstanding balance each month. Your 4.17% would mean you receive a penalty charge each month.