When a coin moves forward to a hard fork is it for good or is it for bad?
Honestly, when a coin forks today it is usually bad. It is just cutting the supporters of that certain coin that they forked.
do you think that its price will rise or fall ?
Both.
would you invest on a coin that has done hard fork?
I won't.
and what would you do if you own a coin that has announced a hard fork? would you sell it or not?
Free money, sell it.