1. No, it doesn't.
2. 4 Hydrogen atoms are on the reactants side and 2 hydrogen atoms on products side.
3. Because the mass of reactants is not equal to the mass of the products thus it doesn't follow the law of conservation of matter.
But on balancing the eqn,
CH4 + 2O2 > CO2 + 2H2O
The above eqn will follow the law of conservation of matter because the mass of reactants is equal to the mass of products.
