Minor Customizations in vTiger

Hi, We have a vTiger 5.4.0 installation which is standard and does not have any customizations/ extra modules/ etc. It's the basic configuration. I need the following: 1. While creating a new invoice: Organization/account should get auto populated when the contact is selected 2. On a Contact Detail page, there should be an action "Create invoice" similar to Opportunities/Potential page Based on the quality of work, there is also performance optimization which needs to be performed. But that will be a separate project. Out vTiger installation is on a shared host, and login /pass and ftp details will be shared.