Should I return my lens?

I have a AF-S DX NIKKOR 18-105mm f/3.5-5.6G ED VR lens.
But I have noticed some lousy work on it.

1. The diaphragm looks like s***, the leaves do not form a nice hexagon, but instead they form an assymetrical shape. Looks like one of the leaves is out of placement. On one exact setting, the leaf is sticking out inside of the shape.
The camera + lens are less than 1 year old, and my 40 year old M42 50mm lens has its diaphragm still holding a nice hexagon.

2. Focuses beyong infinity on manual focus. This sucks while shooting at night, because I just have to guess.

So, what do you think? Should I have the lens replaced or not? Is the beyond-infinity problem model-wide or will getting another piece solve this?

Both of your problems are valid and not acceptable. Unless you've dropped your lens, or it's suffered some other accidental damage, you're covered.

If your lens is a Nikon USA import & you submitted the warranty paperwork, you have a full 5-year warranty. I had an 18-200mm AF-S VR lens with a loose focus ring and the rubber grip slipping loose, and it was completely repaired by a local Authorized Nikon Service center at no cost to me.

The other alternative is to contact Nikon Service and send it out to them.
http://www.nikonusa.com/...epair.page