Eucalyptus. They are from Australia originally and grow to be exceptionally large trees so plant with care (not near buildings because of damage to foundations). It's a fantastic plant for floral arrangements - what you can do is grow one but regularly trim it back and use the trimmings for vases etc. This way you keep the tree in check and enjoy the beautiful foliage.

They're there so any water that gets at the back of the bricks can run out. They're Weep Holes. Lots of people don't bother with them.

I'm no expert but it looks like stained pine to me. Anywhere you could discretely chip off a bit of the top layer to see the original colour?