Wordpress Template Modification and Form Assistance needed

I have purchased a Wordpress template and I\'m proposing to use it as a user-generated news website. I have modified the css/design already (I am a graphic, and sometimes front-end web, designer) and I have uploaded the website to a test domain, but I am looking for assistance in modifying particular elements and functionality of the website:

• Creating a custom user sign-up form, where a user will have to check certain boxes and agree to Terms & Conditions prior to submitting
• Creating a custom form whereby users can write a post (and submit a photo) without having to go into the back-end of the website.
• Creating and placing a button in the header for submitting a post