おいしゅうと思い致します I'm pretty sure is plain out wrong. おいしいと存じます would be better, but I'm not sure it would be natural.
違いかもしれない I think would be better as 違うかもしれない.
Other than that, there are a few things that look strange to me, but I couldn't tell you how to make them better with any confidence.
And yes, であろうとなかろうと is the same as であろうがなかろうが.