It could be worse...

Are the tunnels used by terrorists only or is it like a NY subway tunnel?

From all the intelligence I've seen they are exclusively military use, citizens are forbidden since their highest use is as collateral damage and propaganda about civilian casualties. Most of Hamas dresses in civilian clothing to inflate civilian death claims.

Plus the IDF is renowned for it's rules of not targeting civilians. Dressing as civilians by Hamas is, I believe, a major reason IDF has lost the number of soldiers that it has. Hamas fighters and their surrogates are allowed to get close enough to shoot 1 or 2 before they lose the battle with breathing permanently.