Does a US Patent help us with filing for patents in other countries?

Not necessarily - each country determines patentability of an invention within its own jurisdiction. And even when one jurisdiction cites what it considers to be relevant prior art, which you may theoretically have to overcome in order to receive your patent, the patents cited are sometimes irrelevant. We recently received an international search report from WIPO in connection with our PCT application, however, the primary reference noted in the search report was entirely irrelevant to the present invention. Both a Canadian and US examiner cited that reference in their initial rejection, we noted to them why the reference was irrelevant, and both the Canadian and US applications as patents. So, again, what one jurisdiction may consider to be a relevant piece of prior art, it may not in fact be relevant, or another jurisdiction may cite other relevant prior art.