Hi,
I did the same as you are contemplating. I took my IR initial after about 6 months instructing. I did it with a guy who had gone straight to the IR from his minimum hours CPL course. Now, I am certainly not ace of the base, and would say the other chap was an intellegent sort, but because of the instructing I passed in min time, first time and enjoyed the whole thing. The other chap was still battling away four weeks after I had finished. I never found out if/when he passed.
The thing, as pointed out before, is that you will have massively more capacity to take in the instruction. After a few months of trail lessons, with the most amazing distractions they present to you, a busy ATC environment and many hours really learning how to fly well you will be in a much better position to perform better with the IR, IMO.
I truly believe it saved me a lot of money. When I looked back on my ability and capacity before instructing i would have struggled with the IR, and no doubt would have had to pay for that.
Question 2. Dont think you will have any problem getting a job wherever you get your rating. None at all. There is a shortage out there, and as i posted in aniother thread, I think you are more desirable to a school without an IR.
Hope that helps.
LF