Hi Jamie,
1) I'd vary the intervals week by week. Stops you getting stale and means that you are working at different paces.
2) Never run a full distance/full effort time trial. Why make the effort for no reward? There must be the odd local 10K race to throw your efforts into and get an official time. Doing these max effort runs will do less for your fitness than say a 5 mile threshold run and are more likely to lead to injury/fatigue/overtrained syndrome. The old rule of thumb is for every mile raced you should avoid serious training for the same corresponding number of days. If you are doing 10K maximum effort time trials weekly (or several times weekly!) you are an accident waiting to happen 
When you are a newcomer to running, remember even ridiculous training will appear to give terrific gains initially. These gains don't continue for long.....
3) Yasso 800s are a discovery by a guy called Bart Yasso who stumbled upon a strange correlation between the pace at which you can do a set number of 800m reps and the corresponding pace that you could also run a marathon. I've forgot the full details but basically if your 800m average over something like 10 reps is say 2:47 then you are in 2 hour 47 min marathon shape. Put simply, they're not worth worrying about in your case just yet.
Edited: 06/12/2012 at 09:48