I know jReviews like the back of my hand so I compare everything to it. Can someone tell me the status of these things with K2?

1- meta data. with jReviews you can automate meta data using variables such as {tags}, {title}, etc to the meta data area. This is a HUGE help with SEO and you don't have to set meta data on every article, it does it by itself accurately. You can also leave it off submission page and know that it'll get done.

2- can you easily tease articles so that guests can read some of it and then must register to read the full article (like Joomla content works)?

3- can you set Joomla access, publishing dates, etc from frontend?