Will this track many specific devices like portable heaters, window air conditioners, multiple refrigerators, etc.?

Or does it only track per circuit.

I rent out five bedrooms in my house. The other day I noticed a housemate with her window air conditioner on, the other window open wide. Last winter, another housemate had a similar thing going with the portable heater. I would like to know what all the various equipment costs me, who is leaving their heater on 24 hours a day even when they leave town etc. I have a Kill-a-Watt, but particularly for things in the bedrooms, I would love to know what’s going on without having to go in their rooms. The circuits weave randomly through the house, so it will in some cases be difficult to know specific appliances if that’s the only way.

Also, not clear what I should be buying. Do I need clamps as well and if so for what?

Correct. It monitors circuits, so if the circuits are shared by multiple tenants, you will have no way to identify the user. Sense claims to be able to identify specific appliances. Read the reviews and decide for yourself if that’s something you can use.

I actually found Sense first. The reviews make it sound very bad at it’s alleged job of identifying individual appliances. A disgruntled reviewer recommended this instead, but perhaps not for that specifically. At the end of the day, it sounds like Sense gives an overall picture of total home energy usage, which may indicate a red flag now and then, but otherwise the data is what a utility company generally provides already…Not sure how tracking circuits usage is more helpful. Learning curve!

To monitor individual items you could use a Shelly device - several have power monitoring functions. They are a bare device that you would need to wire into your circuit and ensure no live parts are exposed.

Wiring one into a power strip (either using a Shelly button to contain the device or an appropriate junction box) will enable you to monitor the device(s) plugged into the strip.

So if you find something strange on a circuit monitored by an iotawatt you can use the Shelly on each item in turn to get more info.

They are near instantaneous response automation devices with loads of other uses.