I usually import hundreds of files at a time and try to select as many as possible to add the same keywords to, then I usually select some to remove keywords from some that they do belong, then I go back and row by row add additional keywords to the images.
1. Is there an easier way to do this?
2. Say only one photo I have 4 people keyword and a place keyword and I want to apply those same keywords to other image. Is there a way to do that without having to select other images and click on each keyword separately?
Keywording is usually a manual process, there's no way that Lightroom or any other software will know that you want a certain group of keywords for this photo, and a different group of keywords for that photos. You've got to do it yourself.
However, there are a few ways to speed things up.
At Import, you can assign keywords to the entire set of photos to be imported.
You can select all 4 images, and then assign keywords to all of them, in one action.
There's also the spray can which may be useful: #CreativeFriday – Adding custom metadata to Photos using the Lightroom Spray Can.