Personally the plot is basic but it could work, you just need some good writing skills though.
You need more characters and I wouldn't use a descended of Yoda. There is nothing even remotely close to making us believe Yoda ever had a Girlfriend to get a child with. And he probably doesn't poop them out either. Besides Yoda discourages things like that and would never allow it. What you need is something else then Yoda.
Wookie Jedi? Don't like the idea, and your names could use some originality. Also I don't really like the time period but thats just choice.
I would change Yoda entirely, make somebody more special go to the Dark Side. Make it a fight between two lovers or something, two people loving each other fighting for control, divided by a different opinion. More emotion in it like that, allows for more plot twists and more subtle things in the story.
Another piece of advice but this is more for the story...
Figure out what you want from the start, it will make writing a lot easier. Writing an ending is also a good idea, just because you know how it will end and you will know what kind of things people will go threw, well sort off. Create more characters then you need and put them in at times, its very annoying to have to think of characters with importance in the middle of a story. Not to mention that it will actually allow you to be able to use them earlier on, or at least mention them. Preventing the entire appearing out of no where bit.
Think of every thing special you want in the story and think out what it is, you can improvise a lot while writing and make up a lot of things as you go, but knowing a few things will greatly help. Besides if you know you want somebody to die, or you want a sex scene or you want a speeder race you will be able to make the story up to move towards something like that instead of just having it move around and then suddenly it happens. Maybe it won't look better in writing but i'm sure you can actually make the story better for you, which is the most important part of writing.
Also try safe reading every few pages seeing if you don't like something want to change something. Its a lot harder to do when you have an entire book in front of you trust me I know and I keep on making the same mistake