Minecraft is a one off €19.95 payment.
No, an account is a one-time payment.
It is a one-time payment.
You can play Minecraft from as many computers as you want as long as you log in on each one from your account.
No, it's a one-off payment.
No, it is a one-time payment. There are no additional fees.
Buying Minecraft for the PC costs $26.95 as of September 20th, 2014. It is a one-time payment, and as long as you remember your account information, you will never need to buy another account.
Nope, it's a one time payment.
No. you pay oncee and you have it forever until deleted.
There are several places to go and play Minecraft games for free. One of them is minecraftforfreeplay.net. There your daughter can play Minecraft to her heart's content for free.
No, it is a one-time payment. Additional content is added in the form of free updates, there's a lot of free fan-made content to play with too.
Planet Minecraft and Minecraft Wiki are two sites i can think of.