Using Light meter and Flash

If I use light meter to measure the flash intensity, I guess I can't use ETTL is it? Then If I use manual flash mode, how do I determine how much power I need to set for the flash?

And how does light meter help me into that?

Say for studio shoots, can I just handheld the light meter and then trigger the flash from the camera without using any sync cord to the light meter?

Or should I get and assistant or the model hold the light meter and I trigger the flash from the point where I'll be taking the shoots? As flash intensity will be reduced as distance increase even with light meter giving the reading, I'll still have to measure the reading from at a fixed distance, right?

This would be very different from outdoor shooting where distance between the camera and the subject is not a factor, right?

I'm not sure about the other meters but the Sekonic light meters have a mode called the "cordless triggering" mode. This mode allows you to meter a flash by triggering it manually. What you would do is either have the subject hold the meter close to the face with the dome facing the camera or attach the meter to a stand placed at or beside where the subject would be and then you trigger the flash using the camera or by pressing the Test button on the flash. Just be sure to read the meter manual on how to properly use the cordless triggering mode or you might get erroneous meter readings.