How to keep the water sprays all towards the inside?

When the water pressure exceeds the normal range, spray direction maybe some outside. Maintain proper water pressure to ensure that the water spray is all towards the inside.

Is this product suppose to come with a water pipe?

No，but the product comes with a hose connector. It is easy to set up with a standard garden hose.

How high is the water splash pad?

It depends on your water pressure. If your water pressure is big, the height of the water will be high.

Any tips for preventing mold from growing inside the splash mat and where the water flows?

After every use squeezes the water out and hangs it up to dry outside. Their kind of water toys should be conserved like that.

What type of water pipe suitable to use for this splash playmat?

The normal home garden use pipe is ok for the splash pad.