This program not only did not allow me to do what I hoped to do, but it ultimately broke my website. After unpublishing and disabling all content of K2, my site worked fine. When I uninstalled it, my site mysteriously stopped working and went to an error page. Only reinstalling K2 has allowed the site to work again. So now I have this program that is useless to me being a required component to keep my site up, I guess that does make it useful finally.
1)There is NO way to pull up an Article submission form from the frontend with this program. You cannot set this up in your menus from the menu editing Joomla backend. None of the modules link to an article submission form. The Jomsocial plugin for this doesn't do it. And the default Article Submission form doesn't do it. There's just simply no solution I have found for this. And the documentation is backwards and does not address this issue in any way.
2)The backend tools are just not easy or friendly to use. Every other component I have used had configuration options where it is modified directly within the component menus, pretty much the standard setup for a Joomla component. This is backwards as well, because all this stuff is done from the MODULES. This not only doesn't make sense, and makes it a pain to change configurations from this, but also makes things more difficult if people need to modify the modules for specific things so that it does not break the editing options on the backend in the Module Manager for these modules.
3)Unable to find any easy way to import my existing Joomla articles into K2. Every other program I've used that is supposed to complement or extend the functionality of a similar built-in Joomla function allows you to import data into this new item so you can work with it i.e Community Builder and Jomsocial with userlists, but no such luck here. This should be functionality BUILT-IN to the program.
4) I found no features or functionality that I did not already get with Joomla's built in article setups. I downloaded JCE to make the editor easier/better to use and that helps with Article submissions. So this pretty much was nothing but Bloatware for my purposes. Feel free to try it, but make sure it doesnt get integrated too tightly into your site, you might ruin the site if you need to get rid of this.
You are obviously an impatient Joomla! newbie, so I'll throw in the following facts for you...
First of all, K2 is a standalone component. It does not need any other Joomla! extension to function. It just requires Joomla!. If you uninstalled K2 and your site "broke" I can only guess the following: you uninstalled the component, yet you forgot some menu items pointing to K2.
On to your ramblings now...
1. K2 supports frontend submission by default. Just publish the mod_k2_login module in some position. When you log in through the module, you will see a menu of editing options, including content submission. Set K2's ACL properly and you get a powerful system to handle dozens of writers.
2. What you refer to clearly shows your level of Joomla! knowledge. K2 maintains the "category" display options where it should: in the category. The fact that Joomla! has such options in the menu does not mean it's right. The modules are quite powerful and replace the functionality of at least 20 equivalent non K2 modules...
3. You must be blind, right? The K2 dashboard has a big button top right that says "import Joomla! content". Nothing more to say to that.
4. Of course. Comments, tags, nested categories are all included in Joomla! 1.5...
To finish up, I can either guess 2 things:
a) You either installed K2 and played with it for around 5 mins and that was it.
b) You tried installing K2 on Joomla! 1.6, which is not a stable release and therefore K2 is not yet compatible with it.
My best guess is the latter one...