So whose getting one of these?

Just picked my Tab S4 up yesterday. So far this is a large jump in quality/features from my last tablet. I am upgrading from a Motorola Xoom bought on the release day. My Xoom finally died last month (stuck in a boot loop). So far last night I was just getting the tablet set up. I think I got all of the app I want installed, just need to get log in credentials filled out. I tried the Dex feature last night that is pretty cool. I have a feeling that Dex could help me get rid of my 10 year old laptop.

Here are a couple of questions I have so far.

1. I did notice that when I was looking the my library of apps there were a few flagged as "Unavailable". Is that a permanent thing or is the app just needing to get updated by the developer?

2. Another question is on the S-Pen there is the metal ring near the middle, what is with the part of the metal that protrudes out for?

Thanks in advance!