Any kind of scale (there's triple beam balance's, mail scales, even scales at the grocery store.)
a scale
Pet shops, eBay or maybe a neighbour or friend who used to own a hamster.
Kilograms
Mizan : is an instrument used to weigh things like vegetables, meat, chicken etc.
Well I would say that unless the cat and hamster grew up together since birth with constant contact and no food availability stress, then the cat would see the hamster as a potentially delicious meal, just the same as a mouse. Any thing bigger, say an adult rat, and the cat would weigh up its options as the rat has potentially damaging teeth and is bigger and would fight.
A hamster wheel is used in the cage and is powered by the hamster its self. A hamster ball is what you put the hamster in to exercise when you are cleaning the cage. A hamster ball is heavier so would probably go a bit slower but both are actually powered by the hamster its self so it depends on how fast it goes.
I have seasonal allergies and a hamster. I used to keep my hamster in the basement and now she is in my room, but there isn't really much of a difference. so no i don't think that a hamster would make things worse, but if you are still unsure don't keep the hamster in your room
A golden hamster would probably like a cage that is normal size and a few tubes to crawl in. They also love hideouts at the top where they can rest
The hornTrumpet
I would give it 3-5 weeks, So it can get used to you.
I think no because the blocks would be too heavy to weigh.
Yes, it'd be best for the new hamster who is coming in to the cage. And would be much more sanitary.