eBay

unable to send invoice to customer. A message appears telling me a critical error has occurred. What to do with this????

I just sold my first item and the buyer has asked for my email adress is this normal practise and is it safe?

would like to list and sell my first item but not sure where to start. seems like to much information. this is difficult for people with basic or less p.c skills. Is there a step by step teaching guide or did I miss that one all to gether?