convert to metric

What do I do about my spices, which are too light for my kitchen scale (unless I use WAY too much)? Is there such a thing as a metric 1/8th of a teaspoon equivalent measuring spoon?

Temperature is where I have the most trouble. When it’s 15 degrees, I can never figure out whether it’s in the coolish high 50’s or low 60’s. So it got up to 86 degrees, which would be unsurvivable if it were in Centigrade (?) but is actually around 25 degrees in metric.

Liters are another matter! I noticed the gallon jugs of Ozarka water aren’t a gallon anymore, but much smaller, so I suspect they’re offering less water for the same high price. Bottles are uglier now, but I digress.