This spring I am tearing out and rebuilding my front steps. I am basically building what you see in the picture below, except it will be uncovered. I am not building the portico to go with it.

I was taking a walk through the village where I live and all the older homes with porches have tongue and groove flooring and I found this website that I believe does a good job describing the installation process:

Installing Tongue-and-Groove Porch Flooring (http://www.hammerzone.com/archives/decks/oldporch/flooring/t_groove.htm)

However, I have only seen tongue and groove flooring with covered porches. This makes sense to me because the porch is mostly protected from the elements.

If my entryway is not covered, will tongue and groove flooring still work for me or should I stick with pressure treated decking boards? Do they make pressure treated tongue and groove boards?

Even a protected outside porch should get pressure treated lumber, just like a deck. Installing Tongue-and-Groove Porch Flooring (http://www.hammerzone.com/archives/decks/oldporch/flooring/t_groove.htm)

Thanks Ballenger, pressure treated lumber it is. If the stairs are uncovered should I used tongue and groove or not?

I would use t&g for eother type of porch unless you wanted it to look more decklike. The thing about t&g, you do not want it perfectly flat and horizontal. It needs slight pitch out away from the house so water can never stand or pool. 1/4" per foot should make any water drain off the porch. If you can't set that pitch then skip the t&g, the plain boards will not pool as much and you can space them apart.

Awesome, thanks for the advice.

The picture I posted above has a top platform and a single step. Building the step is simple enough, but I'm trying to figure out how I want to support it. The picture below shows that the step is supported by large stones on either side.

I don't want to use stones. I was thinking of running the concrete walkway under the step. How well do you think this will work? The walkway will be 4-5 inches thick. Do I have to worry about the concrete cracking under the weight of people walking on the step.

Concrete under the walk works for me but it looks like you are almost past that point. You could bury some 4x4 posts inside each corner righ where your hammer head is in the pic. PS concrete should not crack unless you have some really, really big friends.

That pic is one that I grabbed off the net. If I hammered down some 4x4s into the corners of the bottom step, would I have to set them in concrete?

Yes you should bury the 4x4 posts, especially if it freezes in your area.