a) Our ceilings were constructed with plywood (?) that warp with the constant change in temperature. We asked the builder about using Gypsum plasterboard. At the time of construction they had no knowledge of this material.
The gypsum here has no recess on the long edges for tape unfortunately..Filipino`s would have no problem putting the stuff up,but they would have to be shown.. You see it used a lot in shopping malls etc.. Everything they need is widely available here including drywall screws,reinforced tape and joint compound.
We just use hardiflex as it is water resistant and fireproof.. They put that up with no issues.

d) The kitchen units were adequate. However, the hinges used to open and close the doors were of very poor quality and held on by small screws which are coming loose.
We have ours made at our local sawmill joiners..The timber is all kiln dried..Again,no problems getting adjustable hinges these days..All available now.

b) Our kitchen wall smelt damp. When we looked for the cause we knew that the wall was 'added' to an existing boundary wall. Even though this was acceptable, no damp proofing was used. The builder then painted the outside wall with a damp proof paint. However, we doubt this will completely solve the problem.
If the exterior wall is on the boundry line its called a "fire wall" here.. You cant put windows,doors or anything in it.
There is a cement waterproofing product here call "Sahara" you put it with the render mix and it works.
Problem is unless you tell them to put on an inch+1/2 of render they do not.. Usually 1/2" only.

) ALL the plumbing and faucet fittings - without exception - are of very ,very poor quality. We had to spend a small fortune replacing all the taps and shower fittings. Our en suite bedroom needed 20,000 pesos for the fittings. When we came to use the new fittings, there was hardly any water pressure! WE are solving the problem by having a separate tank and pump.
Corrosion is a big issue here with taps, showers, sinks etc..
These days we only use nylon faucets, sinks, etc.
The best we have found are "Watertek" products.
Last years..No corrosion!
You can get non-corrosive pressure tanks here now..Not cheap though. (but worth every Peso)

Best not to use a contractor.
They don't care about what materials they use because it comes out of their lump!