George, SWR meters are all fairly simple, just some wire and diodes and a switch. A grade school
kid could build one if he knew how to solder.
So I'd feel comfortable with any brnad name, as long as it was for the frequencies that you want to cover. The big Daiwa's with twin needles are nice, no need to flip a switch, but really, even a "Shenzen special" should do OK.
As to holding up in the marine environment
and so on...I don't think any of them will be gold flashed, or a problem. Pick a seller that seems reliable, 100% feedback, and you should be OK.
As to operation: yes, you plug
a SHORT double-male coax into your radio
, then plug in the SWR meter as close as convenient to the radio, then another coax going up to the antenna
. The meter stays in place.
If it is a double-needle type, you can just galnce at it, put a dot at "normal" so you can see if that changes with age, etc. If it is the cheaper kind that you have to flip a switch on, switch it to forward, calibrate it, switch it to reverse and then normally just leave it there, again with a dot on the scale to show "normal". Check the forward calibration whenever your guilt nags you, but no need to be compulsive about it.
Also buy a "double female" adapter, so that you can just unscrew both cables
from the SWR meter and replace it with the adapter if at some time you ever want to remove the SWR meter conveniently.