If the type is the type of object, for instance only specific entity types should collide with each other, then this:



Should be reversed. You should check to see if the types are the same before checking if their rectangles intersect. This probably wont affect the collision, but it will slow the game down, especially if you are checking collisions for a large array of entities.

I'm not really an expert in distribution, and I just stuff everything into one jar using the appropriately-named One-Jar.  Other single-jar deployment solutions are possible with JarSplice, Scar, and no doubt a whole bunch of others.  LWJGL itself has a deployment utility, though I can't recall what it's called (Minecraft uses a hacked version of it).

As for stuff that actually installs things into appdata and whatnot, I'd be looking at installers like NSIS or InstallAnywhere

Not really.  It involves using Maven, and if you're using Slick out of bitbucket, the real story is actually a bit more involved than my flippant answer, at least until they start publishing artifacts to a repo (ruben01, you listening?).  There's a guide on the LWJGL wiki, but it's out of date and I don't recommend using the old version of Slick that one uses.

Wow.  I copy-paste a pom.xml, change the name of the project, and type "mvn compile".  But for some reason people think that's the more complicated solution.

This is how I was able to set up Slick2D.

1. Create a folder on your desktop and name it whatever you want, for this example I will say it is named "Slick2D_Files".
2. Open up your browser.
3. Go to http://lwjgl.org/, click download on the left, click latest build (first download link), save "lwjgl-2.8.4.zip" to Slick2D_Files.
4. Go to http://slick.cokeandcode.com/, click "Download Full Distribution" on the right and save it to  to Slick2D_Files.
5. Open Eclipse, create a new project, create a folder called "libs", create two folders inside this, one called "natives" and one called "jars".
6. Open up your created folder (the one one the desktop, the "Slick2D_Files", open the lwjgl-2.8.4 folder, open the native folder, select all the contents (the linux, macosx, solaris, and windows folder) and drag and drop them into your natives folder.
7. Go back to "lwjgl-2.8.4" and open the jar folder, select the lwjgl.jar and lwjgl_util.jar (you might not see the extension of .jar but it's there) and drag those into your jars folder.
8. Go back again to your desktop folder and open up the slick folder, open up the lib folder, select the slick.jar and drag it into your lib folder (the one in eclipse).
9. In eclipse, right click your project and go all the way down to properties, once that is open click "Java Build Path" on the left, then click on Libraries tab.
10. Click "Add JARs...", select the three jar files that you have in your jars folder (located inside your lib folder).
11. Click on the little carrot next to "lwjgl.jar - "Your_Project_Name"/lib/jars
12. Click Native, library location:
13. Click edit, click workspace, inside the lib folder open the natives folder and select your OS system.
14. You're done!

I'm going to edit this to make sure it's understandable, if you have any questions please ask.