CRM customization using vTiger

We have recently launched the CRM system using vTiger for our company. We are planning for the Phase2 for the system with many other features and customization. Before going to the phase2 plan I am looking forward for few customization and rectification into the existing CRM workflow as below 1. Exporting the invoice and other documents as an editable copy instead of only PDF File. 2. To change the CRM calendar look/feel and make its interface and event handling features same as Google calendar. 3. Our Invoicing is missing field like no of quantities for each item. We want to include field quantity. 4. Existing system is able to create auto entries of the calendar task .We need to change the format /subject of the task. 5. Auto email reminder workflow is already setup inside the CRM system but due to few logical bugs we have disabled it now. We want to get those bugs rectified and enable the reminders. This set is the first batch which we think enables us to work with one of the best vTiger developer team and get to know the response time for all our expected fixes. We are also looking forward for the Tech team working on vtiger for future customization and support.