Oh definitely keep up with the Clomid, it maximizes your chances for sure.
Yes, the injections are follicle stimulating hormone, my name brand was Follistim but there is also GonalF which I believe is used in Ireland, same thing though.
No, you don't have to have low levels, it's basically the next step after clomid. They usually try clomid first because it's cheaper, easier to administer and stimulates the follicles a little less. When I was on clomid I got 1 or 2 good sized follies (which is plenty) but with the injections I had 3 or 4 nicely sized follicles, so pretty much doubled our odds. The risk of multiples does go up SLIGHTLY on injections, but if monitored closely the risk is very low and usually at most is twins. Even with my 3-4 follies I only got one sticky bean.
My fertility specialist also put me on progesterone afterwards as a preventative measure even though there was no real indication that my progesterone was low. Obviously I wouldn't have changed a thing with that cycle because it worked, but I know every dr is different.
I think it would definitely be worth discussing with your FS. It was the best thing I ever did for sure