Since I'm an absolutely atrocious artist, is it at all possible to build the framework of the game before even adding artwork/characters/sprites, etc.
It's definitely possible to work on the game mechanics without having graphics in place. The platformer I'm working on I started with no graphics, only drawing different colored rectangles to represent the player, enemies, weapons, bullets, and platforms. Since graphics are (usually) independent from game mechanics it's pretty easy to change them by changing resources or adding resources if you don't have any.
Since the game I have planned is a cross between RPG and RTS, I am wanting to focus very much on mechanics and how characters and the world interact with respect to dialog choices and actions made by the user. I want to focus all my time on how the game will work and how it interacts with the user and worry about realizing the world artistically later. Is that at all possible and is it a good direction to go in?
It's certainly possible, as I said above, to work on a game without worrying much about the graphics, though, it is nice to at least have placeholders. You can find some tilesets and spritesheets available for free use online with a quick Google search if you want to have something to use. Also, if you're interested in making your own graphics, you might want to check out 2D Game Art for Programmers. I consider myself a horrendous artist as well but the posts there are quite helpful.
Are there any engines that are particularly useful? How would I go about engineering the framework?(any tutorials, books or articles would help me greatly)
If you're looking at developing using hardware accelerated graphics with sound libraries (which I would recommend) check out LWJGL, Slick2D, LibGDX, JOGL and jMonkeyEngine. They all have wonderful communities that will be extremely helpful. LWJGL is a Java wrapper for OpenGL that also handles input, sound, and window managing. The others listed, besides JOGL, are based on LWJGL. Slick2D is a framework that handles a bit more than LWJGL and has some implementations of things like sprites and loading assets that you may find helpful. LibGDX allows for simultaneous deployment to PC, Android, HTML5 with WebGL, and iOS (still in the works) and also has implementations similar to those of Slick2D. I'm not extremely familiar with jMonkey but where the others are just frameworks, jMonkey is a full engine. I've heard good things about it. JOGL is another Java wrapper for OpenGL. Take a look at them and see which one you prefer, then go with that one. They all have wikis and tutorials plus helpful forums. You also always have the option to post here for help.
Yes, your game does seem like a lot of work. It may be something you build up to, not something you work all the way through at once for your first game. For me, it's been extremely helpful to prototype a new part of the game in a small, simple app, then implement it into the game itself after I've learned more. For example, when I changed my map to using the tmx format using the Tiled map editor, I wrote a small app that just read in a tmx file and displayed it and allowed simple scrolling. You'll want to start out small and work your way up. Good luck and if you need any help the forums here are a great resource.