John F has no doubt given you some good advice. I'll add just a few bits and pieces from experience.
If you do decide to use nails instead of screws, with treated wood they need to be galvanized nails because the wood treatment will rust out regular nails quickly. Screws need to be decking screws made for treated lumber. Don't use regular screws for the same reason. I use screws exclusively. I make mistakes. If you nail something with galvanized nails, they hold much better than regular nails. You pretty well destroy whatever you nailed together getting it back apart. Screws unscrew easily to correct mistakes or to modify something you decide you want done differently later. I personally like the deck screws with the star drive. The square drive is likely ok too although I have not used them. Avoid the regular Phillips head as they are easier to strip the head and don't stand up to re-use as well(when mistakes are made).
I used to use lag screws for attaching planks. Any more I use exclusively "Spax" brand fasteners. They are available in the big box home improvement stores. Lag screws are grade 2 and are subject to twisting off if you do not drill the correct size pilot hole in harder wood. Spax require no pilot hole and hold much better than lag screws. They are hardened steel and I have never twisted one off (have twisted off numerous lag screws over the years). The Spax are more expensive, but well worth it in my opinion. They are also available in a variety of head styles for specific needs (lag screws only hex bolt head). Do a Google search for SPAX or look them up on store web sites. They also have a flange head so no need for a flat washer. For fastening anything that needs something bigger than deck screws, use Spax.
If you do not have one, get an impact driver. Quarter inch hex drive impact driver. Don't try to use a drill as a driver. I use 18 volt Ryobi (Home Depot) and they work great (we own over ten of them we use in our shop and around the farm) but if you have a name brand you prefer I think any brand would be fine. You may already know this, but if you don't and are building anything with wood and screws, they are essential.
That is all I have.
Last edited by snrub; 05/27/16 10:10 PM.
