quality assurance Questions

I have 5 testNg methods. It will take around 2 to 3 hours to complete the 5 test methods. So I want to execute each test methods in different chrome instance so that time will be reduced. Am executing the test methods using java main class by passing the series file which contains the class name.

I am asking you to please recommend good books to read about general testing of an application.

Suppose you work at company, and a new client asks for his new software. 

You know many tools, Selenium, Protractor, SoapUI, RestAssured, API Testing.

But what is the process you take to start the testing of the client tool?

How do you choose where to start testing from? 

Specific about Automation. 

How do you choose which API calls to test? Which are in the regression test suite?

How do you know how much testing is enough? 

Tests usually dont fail, how do you look for tests that actually fail? 

I have knowledge on tools, and I can do as I'm told, 

but I want to be more as a test automation lead, so I need to have more experience

than just following the lead.

I have been in software test for medical devices/software for the last five years, across three different companies. With my prior two organizations we formally validated our web-based software products only for the one or two most recent versions of Internet Explorer (at those times). Having our software work in Chrome or Firefox were nice-to-haves, but we did not communicate to our customers that we supported those browsers,  I'm soon to start work on a major release of an existing product, and the Project has decided to officially test/validate only Chrome, based on our current knowledge that the current release has known issues with IE. Seems to me we could be taking the easy way out, and not taking into consideration what our users use (often by policy). Apparently we don't currently have that information, though, I have brought it up that we should try to figure that out. 

Historically, hospitals/labs/medical offices/etc have - by policy - typically only employed IE for business use, but I know market share in this sector has been shifting to Chrome. But how much/fast? General browser usage, and even entrprise usage statistics are easy to come by, but I'm banging my head at this point trying to find information specific to healthcare/medical research. 

What are your experiences/thoughts on this?

Currently, we have created a reservation system using outlook rooms. Each test environment within the lab has a "room" that someone can book in outlook and gives the user/tester the ability to see what labs are available. However, there are limits to the amount of information that can be supplied for each "room" and it really is not easy to see further details of the "room" (server image, server os, sql server version, application versions, etc). 

I know about LabAgenda, and may pursue this. But is there any other systems out there that people prefere?