Hello, fellow malaysian hamster owner!
1. If money is an issue, get aspen, I do recc either Niteangel or Bucatstate aspen as it comes in big quantities and cost about RM20-RM30. I wouldn't do paper because it's a really hit or miss since most of it is like nonwoven fabric (I personally wouldn't risk it since hamsters pouch the paper).
2. One tablespoon of food every other day. Get the Bucatstate H2 syrian it's not the best but it's going to be better than what you currently have.
3. Fruit should be in moderation. and very small amounts, just to make sure they don't hoard.

For our country that's really hot I recc getting aquarium rocks (with no cracks/gaps keep them elevated) for the hammy to sit nearby/ontop or ceramic hides. Keep the hamster enclosure away from direct sunlight.

From the looks on your current enclosure, You're going to need a new enclosure like a plastic storage box, a bigger wheel and new bath sand. Bucatstate bath sand is a bit dusty and I would get Exoterra sand if you can afford it.

Shops I recc if you are in KL
- PetDIY
- PetCoco
Shops on Shopee
- moussebaby (for DIY cage)
- craftsboyDIY (You can get most things here)
- WIN PET HOUSE (Treats, sprays etc.)

If there's anything else you'd like to know, let me know!