Yes. Both singular.

It would sound strange. You need the בא in both places.

What he said.

correct. you should read the other comments...

Do you come or does he come?

"you come" doesn't sound right in English.... although "do you come or does he come" is totally right, you should report that.

I have the same problem

No, never. it should be at the end of the sentence.

It should be known that Hebrew is read right to left. Therefor the question mark may look like it is in the beginning, it's at the end.

You put it at the beginning of the question. You can actually put it at the beginning of this sentence and It'd be correct. It's very formal though, and can often be omitting, especially on casual manner of speaking

Remember that Hebrew is read from right to left. So, if the question mark is the left-most character, then it is at the end.

Not really. I assume you mean that it seems arbitrary that בא is sometimes translated as "come", sometimes as "is coming". That's done because Hebrew doesn't distinguish between the present continuous and the simple present. For clarification, the present continuous (or present progressive) is "is coming", and the simple present is "come".

Sometimes the most natural way to express an idea in English is with the continuous aspect, but other times it's more natural with the simple present. Hebrew just always uses its plain ol' present tense. :) As a result, you will sometimes translate the Hebrew present tense into the English present continuous ("is coming"), and sometimes into the simple present ("come").

Hopefully I correctly understood your confusion (just let me know if I didn't!) I'm just a beginner myself, so if any more knowledgeable people have corrections to my answer, please offer them. ^^

There's no difference, in Hebrew there are no tenses like the present simple/progressive, if you want to emphasize your meaning you'd add some time expression, such as 'is he coming now?'