Am i able to use Pin to for INT0 if i have already used it fir LCD?
You mean use it simultaneously as an output and an input?
yes!
No.
At any one time a pin is either an input or an output, never both. You can switch between the two but that won't work for you because an interrupt could occur at any time. If the pin is an output at that time then you will miss the interrupt
What problem are you trying to solve ?..
Thank you!