Please help me correct this.

Which word or option is correct please?

You see him practice/practicing for half the movie.

Don’t make it harder than it has/needs to be.

That way the only thing I’ll have left to do is math homework when I get home.

That way the only thing that’s left for me to do is math homework when I get home.

When you are drunk it takes you longer to do things./ things take you longer to do. (What is the difference?)

thank you