Can I store it in a glass jar?

You can just use the Nutella. I eat plain Nutella with apples all the time, it's delicious.

As long as the glass jar is freezer-safe, yes. Do not freeze anything in glass if you are unsure, because your glass could crack.

Yes, but the jar should have air holes and may be harder to clean because of the small space.

Yes! Roasted rice is also sold in bulk either canned or in bags.

If you’re trying to melt old candle wax in its original jar, you can do so by carefully placing the jar in hot water inside a double boiler. Avoid letting...

Yes, you can store an excess of the paste in the refrigerator. Unless you freeze it, I would use the refrigerated left-over paste within three to four days.