consult this chart i guess

http://rideyourbike.com/images/skidspots.jpg

Yes its a full wheel. The chain ring is just like the one you have above. I think the one has 36 teeth and the other 50? Not completely sure I counted right.

Its probably around there. Those will be hard to match up with a cog for a good ratio. Consult the chart and decide from there.

50/19 is a decent starting point. 71 GI isn't too hard/easy

I'm not really sure how to read this chart. I'm guessing you want to try and stay with the green numbers?

Yes, I was also going to recommend 50/19.

Lower the gear inches, easier to skid and go up hills. Higher the gear ratio, harder to accelerate, pedal less to go faster.

Low 70's is always good. Im running about 73 right now.

Well... the problem now is the new flip flop hub is free/free (but it has two different sizes). So i'm back to square one on the wheel part

as of not im just running it single speed until i cant get a new wheel set

Got myself a new wheel.
Its fixed now.
Here she is
Attachment 156075

just found this thread searching for how to do a DIY fixie and I am a little disappointed that a home made fixie hub wasn't achieved. On the other hand I can't say that I am surprised. I really like the way your bike turned out and it's awsome that you used a bike with a cottered crank. That is definitely working with what you have got. Nice work!

So you used the 36t ring? What size cog did you get? And how is that working out? Good job by the way, getting a fixie going on the el cheapo!