I've got minimal security settings

Then you don't need to provide user and password.

  I can use this method right Login(Username As %String, Password As %String)?

No. First line of script - user, second line - password. After that - ObjectScript.

Do $system.OBJ.Load("Installer.xml", "c") I dont know why. 

Try full path. Also this method returns status, check it:

Set sc =  $system.OBJ.Load("/path/to/Installer.xml", "c")
Write:('sc) $System.Status.GetErrorText(sc) 

First two lines of your script should probably be user and password, unless you're running a minimal security install or enabled OS authentication.

ObjectScript code after that, yes, sothis looks correct

do ##class(User.Installer).setup()  

Maybe you need to load User.Installer beforehand?

Use $system.OBJ.Load(file, "c") to load and compile class(es) you need.

Use ccontrol qlist to get structured information about available instances.

ccontrol qlist [<instance>] [nodisplay > outputfile]
Display a quick list of information about all installed instances, in a format suitable for parsing in command scripts.
The record for an instance contains fields separated by "^" (carats):

  • Field 1: instance name
  • Field 2: instance directory
  • Field 3: version identifier
  • Field 4: current status for the instance
  • Field 5: configuration file name last used
  • Field 6: SuperServer port number
  • Field 7: WebServer port number
  • Field 8: JDBC Gateway port number
  • Field 9: Instance status (e.g., ok, warn, alert)
  • Field 10: Product name of the instance
  • Field 11: Mirror Member Type (e.g., Failover, Disaster Recovery)
  • Field 12: Mirror Status (e.g., Primary, Backup, Connected)