Does it protect against power surges?

No. It is a plain outlet splitter rated 15A/1875W, not a surge protector. For electronics you want protected, pair it with a surge strip or a surge-protected wall tap.

Will it hold heavy chargers without falling out?

The included center screw fastens the tap to the outlet so it stays put under the weight of adapters. Without the screw it relies on plug friction alone.

Can I use it in a kitchen or with a space heater?

It is rated for 15A and 1875W total across all six outlets, so small appliances are fine. A space heater or other high-draw device should be the only load, and check its wattage against that limit.

Does it work in a standard two-plug outlet?

Yes. It plugs into a grounded duplex outlet and covers it, giving six grounded receptacles. It needs a grounded (three-prong) outlet to mount and ground properly.

How is it different from a power strip?

It has no cord and no switch, so it sits flush on the wall and adds no floor clutter. A power strip reaches farther and often adds surge protection, which this does not.