The examples you give which involve killing are ALREADY covered by the rules. They would be war crimes, humanitarian crimes or straightforward civil murder. Even a particularly difficult one, insurgents embedding themselves in the civilian population, is clear-cut. If by doing so they endanger the civilians, they are guilty of crimes against humanity. If you attack a house where there is a likelihood that insurgents or soldiers are holding civilians, that is a war crime. What some people are really looking for is an excuse to suspend ALL rule of military and civil law when fighting insurgents. The problem is you are immediately one inch away from My Lai or worse, so no international court is going to buy that. It is perfectly possible to fight an asymmetric war legally and successfully under the present rules, as armies and their legal departments know full well.
Former ruling party in Yemen says it accepts UN-brokered peace plan (Reuters)
from the article: Solana to Haaretz: New rules of war needed for age of terror