will these work on my product?

I don't know what product you are using. However, I use Max Factor pan stick, and it works fine. It will probably work for you also.

Is the illuminsta and nude master blushes the same?

They are really close but the nude has less white and pink in it. It is a bit darker in hue, more like very light skin color. The other has pink and white swirled in but is also very light in color. Both are shimmery. Not super pigmented at all. Better as a subtle highlighter than blush in my opinion. I got the darkest one and it barely gives me a blush but does highlight nicely over a subtle cream blush I use.

Does this contain isopropyl myristate?

Just went and read the back of my blush and didn't see isopropyl myristate listed (I will not even try to pretend to know what the heck that is :)). So in short.....no, it is not listed on the back of the blush.