Sorry, I'm not sure I fully understand what you're trying to describe here? The custom forms feature in Vantage allows to you create a custom form for listings in specific categories, so basically a customer selects the category they want, and the appropriate form appears for them to complete.
When you refer to a custom homepage that links to specific categories, do you mean something like
this customer site from the
AppThemes showcase, where the customer can select the relevant location? (My apologies if I'm way off mark here, just trying to picture what you are looking to do)