If I recharge diamonds am I getting credit for the number of diamonds I buy or is it I have to keep..

It's both. You contribute to your V level and you get diamonds. You can also choose what pack you want if you don't want to get diamonds. In the top left corner there's a user pack icon. There you can choose if you get stamina, coins, star coins, etc. in addition to those you get points towards your V level.

More questions for Love Nikki, the Miraland Quiz and other events can be found on our Love Nikki answers page here: https://www.appgamer.com/love-nikki-dress-up-queen/answers/

Is it safe enough to use to use your credit card for recharging