Outdoor decorations?

I'm getting married outside and I believe the country club is only providing an arch of some sort- as well as chairs and a runner of course. I've never been to an outdoor wedding so I have no clue...

Do I decorate chairs like you would pews? The arch itself?

If so- with what? Bows, flowers, tulle???

Since there's no alter, should I assume a unity candle is out of the question?

Will we need microphones?

Is this something that's DIY or should I consult my florist?

Yikes!

Any help in any of these areas would be GREATLY appreciated!

Thanks,
Lauren