Is it possible to host multiple sites with a single hosting account.I mean if I gets unlimited subdomain from the host & setting up multiple sites like forum, wp blog etc from single hosting account & linking them to a top level domain name so that it looks like they all are unique sites.Hopes it explains what I needs to know.
If you have unlimted subdomains you can have as many sites as you want in this manner. forums.mydomain.com blog.mydomain.com neat-stuff.mydomain.com On the vast majority of hosting plans it is even possible to host more than one domain name on a single account using addon domains feature: domain1.com domain2.com and so on to the limit of your account.
The best method is to check with your host and see if they support you hosting multiple domains on one account. I know my host allows me to, so just use their contact methods e.g. live support or contact forms
More database quota than you are ever going to need or use on a shared hosting account. Nothing to be concerned about.