Consulting firm needs: How do I create recurring invoices from a project? Track resource costs for project profitability?

Consulting firm needs: How do I create recurring invoices from a project? Track resource costs for project profitability?

We're trying to move away from using Zoho Projects for time tracking as our consultants find it difficult, and instead use timesheets directly within Zoho Books.

As a services business we automatically invoice many of our clients monthly for services and need to track the time of our consultants against these monthly services.  We have recurring invoices set up, and we have projects and timesheets set up, but there doesn't seem to be a way to connect them.  I don't want to manually create an invoice from each project each month yet there doesn't seem to be an option to create a recurring invoice from a project. 

Also, if the invoice was set up before the project, there doesn't seem to be a way to connect the two.

Finally, I see that I can set hourly prices by resource but not hourly costs.  How can I see my project P&L?

Thanks,