Repair a hole, from a leaking pipe search, in concrete shower floor

Hi all

I have recently moved homes and the cold pipe in the shower was leaking. We had a plumber come in and find the leak and repair it (as shown in photos). I have let it dry out for a couple of weeks and am after some advice on how to concrete in the whole in the floor. My plans are:

1. Remove tiles another two rows higher (more if needed), they sound hollow when knocked.
2. Form up the hole under the house.
3. Insulate/cover the water pipes. I am not sure what to use for this - any ideas? The plumber thought the original pipe split due to it being in direct touch with the concrete and twisting when in use.
4. Concrete - what would be best/easiest to use, I was considering painting the edges of the current concrete with bondcrete
5. waterproof
6. tile.

I would love to do the whole bathroom but budget limits my capacity. Any feedback would be greatly appreciated

George