It is not possible to sync the project milestones and meetings with the calendar in Zoho CRM.
The tasks, meeting and milestones assigned to you across all the project can be seen in the Google Calendar with the help of the gCal link available in the Calendar tab. Learn More.
If you are the Portal Owner, you will be able to create invoice for the billable timesheet entries from Zoho Invoice.
Contacts can be imported from CRM into Projects once these services are integrated with each other. To integrate these two services, refer the link Import contacts from Zoho CRM
Zoho Projects and CRM can be integrated with each other. Refer the link mentioned below to integrate these two services.
If you don't access your configured Dropbox account for more than 15 days, the sync process will stop.
Yes, you can file bugs from Zoho Support, if it is integrated with Zoho Projects. Learn More.
Yes, you can integrate with Github and host your repositories, view source commits and make code changes. Learn More.
Zoho Projects is integrated with a bunch of third party tools such as Dropbox, Google Drive, Github, Bitbucket, and more such apps. Learn More.