The resistance between pri-sec is a bit more worrisome, but at those levels the ohmmeter can be very susceptible to external factors.
Yeah, cause I was expecting pri-sec should have infinite resistance, but what external factors are you talking about ? As the transformer was not connected to anything except the LCR meter.
As all LCR meters I know put out AC at various frequencies, any capacitive coupling may cause it to falsely read current flow, thus skewing the measurements.
Obviously that you can simply try to test with a regular DMM's ohmmeter (which only puts out DC) and see if you have any of such effects in your measurement.
If you have a Variac, all your questions will be answered. 
Start at really low voltage at primary using variac, and slowly crank up while measure the secondary ?
To be honest, all my meters are maxed out at 1KV, and quite scare as this is lethal voltage, still thinking how to properly isolate the output terminals before I start powering it.
Exactly. Start at zero on the output of the Variac and increase it but never go over 14V.
For your transformer the turns ratio is
15.000V/
220V = 68
The maximum input voltage then is:
1.000V/
68 = 14V
The best way to experiment with this is across a very large area and clean of debris and other junk - if you want to do this on your bench, make sure it is clear of pliers, components, vises, screwdrivers, metallic boxes or plates, etc. Give wide clearance between wires on the high side and, if possible, keep them lifted off the ground. Don't rely on probes and use alligator clips on connections - you can also insulate these connections with insulating tape.
Once you get the high voltage bug, you can't shake it anymore off you.
