"should i firstly MOV P2,#00H so that P2 becomes logical low so that controller can respond to a High Signal?"

Have you read the replies at all? Setting a port pin low will make it unsuitable as an input pin. Also, design your circuits so that 1=off, and 0=on. Do it now, or regret it later.

In your case polling is the most suitable solution, because what happens on the different port pins is completely unrelated. For you the JB/JNB way is the way to go.