That should work.. Assuming you are feeding AC through the unit on the right, and not providing DC to the switch etc.?
12V *might* be a little low for the LGB point motors.. Usually use the 16-ish Volt AC output from one of their transformers.
To add LED indication.. I presume you mean for signals?
You need a DC supply, and the add-on switch for the point motor. - You only have volts to the motor when you operate the switch.
It then depends on the supply you have available, and whether you want individual LED's for each aspect, or want to use bi-colour LED's.