Hey Sintara,
You'll get it working pretty fast, don't worry! Some Youtube users make it look easy because they've already been through their first day or two of confusion and didn't upload all that.
It sounds to me like you have a few different issues, the very basics are that Voice Attack gets its input from the Windows Voice Recognition system and that doesn't handle background noises well - it needs clear pauses (silence) between words or phrases.
"99% of the time simple words wont be recognized like hello."
Start by checking that you are using a headset microphone and that the mic can only hear your voice. Turn the headset volume down low so that you can barely hear it to help with this, as many headphones will leak sounds that the mic picks up. The mic should not be right in front of your mouth or where your nose breathes into it - try swinging the headset mic up over your nose, in front of your forehead.
You will probably have to play with the (Windows) Sound Control Panel and set your mic input volume to less than 100% as well - distorted sounds are harder to understand. Voice Attack shows microphone volume in the bottom bar of its window, you want this not moving unless you are actually speaking, and then you do not need it to move all the way across to the right when you are talking at normal volume. If you have a TV on in the same room it just will not work.
Doing the boring Speech Training which you can find in Windows Speech Control Panel is important before trying to run the Universe, it helps but you have to do it more than once. Gary, the author of Voice Attack, recommends going through both set texts twice. One is about the history of speech recognition and the other one must have been even more boring because I forgot it already. You need Voice Attack to NOT be running while you do this training in Windows - don't run both at the same time as they fight.
Very short words like "hello" often cause problems because they can sound like other things. Try, "Greetings Midnight" to give him a better chance to understand you after doing the steps above.
If you want to know how well this can all work for you, look up Bearzly's Voice Only Dark Souls run and be amazed:
https://www.youtube.com/watch?v=5m2a2dLdZ0M(Voice Attack is showing as the white box bottom-centre and you will see that even though it's recognising short commands like "heal" perfectly, as soon as he talks to the viewers it thinks he's saying complete nonsense.)
The other issues you mentioned,
"im getting him speak twice my keyboard wont work 100% if VA is active"
I am not sure about but I am sure that someone more experienced will know and help you out with troubleshooting for those.