"love and kisses" or "hugs and kisses" are not uncommon, but these
would generally only be used for family, usually an adult writing to a
child or a maybe a child writing to an adult.
Adding an x to the end of an email is quite common amoung young
people. Girls will tend to do it to any friend of either
sex, and some lads will tend to do it to any girl. This does not
imply an attraction.
People who do this will to add a single x all the time. eg:
... I'll see you at the weekend.
John
x
In SMS text messaging an x is often added without even a name, eg:
I'll see you at the weekend.x
I would be wary about using more than one x. Usually three is ok
from a girl, but from a lad to a girl it might mean that he fancied her.
Using any number of x's to family is fine.