Being nice to people is a good thing. What makes God happy is having a right relationship with Him, because of faith in Jesus. The barrier of sin will be removed. There is nothing we can do that will be enough, only what Jesus did to save us.
Happy? My guess would be, yes. However some according to some Christians, you will not get into heaven. To them you can be the perfect human in every way and if you don't accept Jesus you will not get in.
Yes but you live life to serve for him. Do more than that. Pray, as often as you can, tell him what you did wrong today, apoligize, and ask for forgiveness. I think only Catholics do this but understand "fear of The Lord" which I'm still trying to figure out. Crazy Catholics!! I'm just joking, they're right though, do not think you will get away with things without god punishing you. Do a confession, at least once a year, with someone like a preacher, or just a normal friend.
In Matthew 22:37-39 Jesus explained what the two most important principles in our lives should be. He said: "‘You must love Jehovah your God with your whole heart and with your whole soul and with your whole mind.’ This is the greatest and first commandment. The second, like it, is this, ‘You must love your neighbor as yourself.’"
Therefore, being nice to people is only half of the equation. God asks us to love him as well. Since these are principles, it's a way of life.