When I'm in a deep frying mood, I don't change or clean my oil. I usually only do french fries so it lasts me a couple of weeks or so, until the oil smells funny. If I do any meat, the oil deteriorates faster.
Freezing should be fine, though I've never tried. Freezing would separate out any water thst might have accidentally gotten in your oil. Refridgeration would be good as it would separate out any animal fat which you can just skim off. Refridgeration should be enough unless you're talking very long term storage.
Freezing breaks down oil ? Something I'll have to research....doesn't make sense to me.
The trans-fat issue..... something else to look at....... but then how many of member smoke.....?
Vegetable oil as diesel replacement....... after processing, only problem is some of the hoses need replacing periodically as they will deteriorate. Mileage is slightly lower than normal diesel. Mythbusters test showed about a 10% reduction. Yes, your exhaust will smell yummy.
You can use it for quenching your blades after heat-treating (knife-makers).