Create custom Objects in Salesforce

We need to create 2 custom objects that will be attached to a lead they are associated with. We will be using one for customer service issues, and the other will be created and used to capture information posted via API. *First Object* Needs a button or link on the lead to create it Needs to be attached to the lead *Second Object* Needs a button or link on the lead to create it Need the ability to be created from PHP script using API. Needs to be attached to the lead Ex. External application that has SFID for the Salesforce Lead, needs to be able to post to php script that will create a new object.