You can replace the regular garlic with 3 cloves of the smaller native Philippine garlic.
The amount of fish sauce to use depends on individual tastes and, even more importantly, the kind of fish sauce that you buy. I find that Philippine fish sauce tends to be saltier than, for example, Thai fish sauce. So, use more or less according to your personal preference.
Any type of long green chile pepper will do.
You can substitute coconut cream with coconut "gata" powder mixed in water to make the same amount.