The operating system of the server you are on is maintained by TotalChoice. The contents of your site are your responsibility. Not knowing what is on your site it would be hard for someone to let you know if it needed updating or not. If you are using a content management system I'm sure there have been updates to it and they should be applied. If you are running any scripts they may or may not need updating.
There is nothing you can do to prevent spam. If you have a domain, you will get spam. You don't even need a domain to get spam, you can get spam just by having an email account (anywhere).
If you have concerns about your account you can open a ticket with the help desk and ask the techs to have a look.