On our ModX website we have a LOT of contact forms and I am looking at replacing these with the web-to-lead versions (or is it possible to just modify our existing forms?). Before doing this, I need some assurance that:

1) people can't hack into our Sugarcrm database from the form code. I mean if the form can input data into our database automatically, might not somebody else be able to as well?
2) we won't get inundated with spam - our current forms all have captcha-like form validation where users have to enter a code when submitting

Ideally, since we have all of our forms set up throughout our site, is it possible to make modifications to those forms so they can integrate directly into Sugar or do we have to use the web to lead function in Sugar?

Thanks