And if you don't have labels, adding them wouldn't break existing code.

For example you have this routine:

TEST
    write 1
    write 2
    write 3
    quit

It, when called would output

>do ^TEST
123

If you then add a label somewhere:

TEST
    write 1

MYLABEL
    write 2
    write 3
    quit

The routine would wok the same on previous calls:

>do ^TEST
123

But you'll also be able to call only the label:

>do MYLABEL^TEST
23

There's no default function to do it, but you can easily develop your own custom function. There's $IsValidNum ObjectScript function, which could be used to check that variable is a number. So something like this should work:

/// Functions to use in rule definitions.
Class Custom.Functions Extends Ens.Rule.FunctionSet
{

/// Returns 1 if a string is a number, 0 otherwise
ClassMethod IsValidNumber(string As %String) As %Boolean [ CodeMode = expression, Final ]
{
$ISVALIDNUM(string)
}

}

SendRequestAsync is available in all Ensemble Hosts (Services, Operations, Processes).

For Operations and Services the signature is:

Method SendRequestAsync(pTargetDispatchName As %String, pRequest As %Library.Persistent, pDescription As %String = "") As %Status

And for Processes the signature is:

Method SendRequestAsync(pTargetDispatchName As %String, pRequest As Request, pResponseRequired As %Boolean = 1, pCompletionKey As %String = "", pDescription As %String = "") As %Status

In the future please don't combine separate questions into one post.

I am looking for a way to detimerine if a certain namespace is ensemble enabled.

To check that some <namespace> has Ensemble enabled call:

write ##class(%EnsembleMgr).IsEnsembleNamespace(<namespace>)

where <namespace> defaults to current namespace.

Log some information to the console log file with a certain error level.

%SYS.System class provides the WriteToConsoleLog method, which you can use to write to the cconsole.log file.

- If I have a global available in a certain namespace, can I use InterSystems SQL to query those globals?  

- How do existing globals and creating classes work?  Like I have a Person global right now.  Can I turn that into a class and manipulate the data that way?

You'll need class mapping to query globals via SQL. Check article series  The Art of Mapping Globals to Classes by @Brendan Bannon.

- I'm used to Java where you can write a class and then write a driver class to test your classes and methods. Or simply just test your newly created classes and methods in the main method (wherever that lies in your code).  Is there something similar in Studio?  I can write classes but then they are compiled and I have to go to the terminal and test them?  Is this where routines come into play in Studio?

You can configure Studio or Atelier debugger to run any class method. There's no need to use routines for that.