First, generally speaking, there is no right answer to whether you should file the national or PCT filing first, it probably depends on you exact circumstances, and possibly what country you are in (and what countries you want to market in). Just because you have a set priority date does not necessarily mean there is no advantage to having an issued patent in a country sooner rather than later, for example in the US you have to have an issued patent before you can take legal action against an infringer. Therefore, there may be at least some advantage to filing in a country(ies) as soon as possible.
Also note, things get kind of complicated here especially because things work differently in different countries.
Anyways,
1.) This is tough if not impossible to say - chances are it doesn't matter and perhaps both A and B are wasting their resources. Assuming both applications are equal in quality, and are eventually turned into national patent applications in all the same countries (and assuming this is a patentable invention in all countries concerned)...the US is first to invent, so technically in the US the rights to a patent would go to whoever could show proper evidence of the earliest invention date, though that could get messy and bothersome. Many countries are first to file though. From what I gather, in these countries if two identical (in coverage, etc) patent applications were filed on the same day (and/or had the same priority date), only one patent can issue and the applicants would have to come to an agreement as to who it would issue to. But don't take my word for that. My guess would be, whoever sees a patent issued in a relevant country first would likely have at least slightly more leverage in any related negotiations.
2.) If the quality/content/results of applications are equal, in first to file countries B will have priority relative to A (even in a first to invent country like the US, relevant interference proceedings can be a pain). "A" may be wasting its resources, but who knows, depending on exact circumstances if it can get its patent issued before "B" can, perhaps it can then sue "B" for infringement and then if "B" is cash strapped maybe "A" can bully "B" into entering into a relatively favorable cross licensing agreement instead of protecting its rights in court. Or something like that. I don't know why I bother writing this, bottom line is "A" may be screwed on certain levels in this case, regardless of what it does.
There are some good attorneys that post on this board, and there are those here with more legal expertise than I. Yet I don't see anybody being able to give any worthwile guidance to you in a public forum. Bottom line, before you would go through with all this, you would want to find a trustworthy attorney.