I would do the first part in PHP and store the form data in MYSQL database
This would be the best solution
Maybe look at a CMS development.
Cost for this could be as little as a few hundred to a couple of grand but remember that the cheapest is not always the best
The second part of your requirements are a bit vague and overly complicated
You are wanting to replace the domain with another or mask it anyway.
This is not possible
You can mask URLs regarding querystrings etc
[example]
masked to