You should know, that namespace it is a just definition in which databases stored some types of data, and how it mapped.

So, you can only check in which database package stored

write ##class(%SYS.Namespace).GetPackageDest("SAMPLES","%Activate.Enum")
^/opt/cache/mgr/cachelib/

delimited output, first part is a system like in ECP-configuration, and second part is a database path

you can compare this path with default path for packages in this namespace.

w ##class(%SYS.Namespace).GetPackageDest("SAMPLES","")
^/opt/cache/mgr/samples/

You have two cases, you change storage definition or you can use calculated value. But in case with calculated value, you have two options. It's an object's access and sql access, and such getter it is just only for object's access. For SQL you should define SqlComputeCode. Something like this.

Property Invalid As %Library.Boolean [Calculated, SqlComputed, SqlComputeCode = { s {*}={+$G(^GLOBAL({Code},"INVALID"))} }];

more details in documentation

There are no particular recommended SourceControl systems. Everything depends on your choice.

Some time ago, with versions cache less then 2016.2 and before Atelier was appeared, we could use nothing except Studio. And in this case to work with particular SourceControl we should write own addon for Studio as a wrapper for this SourceControl. You can find one as a good example here on github, which works with GIT

Now, when we have Atelier, we could forget about this part, and use lots of available plugins for different SourceControl systems.

BTW, I prefer git, but most of time used SVN at work, and git for my own projects.

It's a right way, but don't you think, that you forgot to save your changes ? something like this

w rtn.%Save()

or you can just use $system.OBJ.Load("les.mac") or $system.OBJ.Load("some.class.cls") in versions 2016.2+
if you have less version but not less then 2014.1, you can load class with %Compiler.UDL.TextServices  as I've already offered to use it for export on stackoverflow

Every routines stores directly in database, so, you can't just open it as any file on your filesystem as well as you do it with csp files.

but you can open it with %RoutineMgr class, something like this

USER>zn "samples"

SAMPLES>set rtn=##class(%RoutineMgr).%OpenId("hello.mac")

SAMPLES>while 'rtn.Code.AtEnd { write !,rtn.Code.ReadLine()}
 
hello ; hello world routine
 write !, "hello world"
 write !, "bye"
end quit  ; end
 

if you also need to get list of such files, you can use query StudioOpenDialog in %RoutineMgr class

SAMPLES>set st=##class(%SQL.Statement).%New()
 
SAMPLES>set sc=st.%PrepareClassQuery("%RoutineMgr","StudioOpenDialog")
 
SAMPLES>set rs=st.%Execute("*.mac")
 
SAMPLES>do rs.%Display()
 
 
Dumping result #1
Name    IsDirectory     Type    Size    Date    Description     IconType
DocBook .       9                               0
badroutine.mac          0       62      2004-09-28 13:05:45             0
CinemaData.mac          0       10258   2016-05-10 22:32:04             0
compareloop.mac         0       1201    2004-12-02 18:23:57             0
datent.mac              0       3089    2002-01-03 12:05:01             0
datentobj.mac           0       2627    2002-09-06 00:15:23             0
dbconvert.mac           0       1532    2002-01-03 12:05:52             0
fibonacci.mac           0       365     2002-01-03 12:06:03             0
forexample.mac          0       502     2004-11-30 16:00:08             0
funcexample.mac         0       333     2002-01-03 12:06:30             0
hello.mac               0       251     2016-07-13 12:07:04.520803              0
LDAP.mac                0       68720   2013-12-16 11:48:09.962335              0
lookup.mac              0       8484    2008-08-21 19:17:48             0
lookup1.mac             0       1465    2002-01-03 12:07:15             0
lookup2.mac             0       5984    2002-01-07 18:08:46             0
lookupobj.mac           0       7857    2008-08-21 21:58:25             0
loopend.mac             0       242     2002-01-03 12:08:12             0
loopstart.mac           0       217     2002-01-03 12:08:21             0
nameloop.mac            0       552     2002-01-03 12:08:33             0
passbyref.mac           0       604     2002-01-07 12:01:47             0
postcond.mac            0       341     2002-01-03 12:08:51             0
procexample.mac         0       423     2002-01-03 12:08:59             0
publicvarsexample.mac           0       357     2002-01-03 12:09:09             0
RightTriangle.mac               0       1836    2011-02-24 18:56:29             0
root.mac                0       149     2004-11-30 15:57:29             0
simpleloop.mac          0       161     2002-01-03 12:09:59             0
SQLGatewayTest.mac              0       2480    2016-05-10 22:32:04             0
survivor.mac            0       179     2002-01-03 12:10:32             0
ZAUTHENTICATE.mac               0       37302   2015-03-10 10:48:43.589807              0
ZAUTHORIZE.mac          0       12120   2016-05-10 22:32:04             0
 
30 Rows(s) Affected