Depends if you already have an account with them and your age. if you are successful, they will send you a load of forms to fill in and return. If you do not have an account with them you will also need to prove your identity by taking them into a branch.
On the whole, probably easier to just go into a branch
Yes, as along as you are 16 or over and hold a Bank Account for Under 19s, Classic or Select account. If you are over 18 I agree with the last entry, you are much better having a full debit card (you would need a decent salary to be credited each month). Hope this helps.