I don't think you should apply to a course on the premise that you think it will boost your chances of getting in to Oxbridge. The applications process is competitive, and you need to show that you have a deep and passionate interest in the course you have opted to read. The interview panel will see through an application which is not well founded, so if anything, it is likely to hinder your ability of getting a place to opt for one course you like less over another. I'm sorry to sound as if I'm being harsh, but it is probably true.
If you do apply for a course which you don't enjoy, chances are you are going to have all sorts of problems with it. I have personal experience with this, although my original course was one which complemented my A Levels and one which I truly thought I would enjoy. I couldn't have been more wrong; the course was totally different to A levels. Even after all the research I conducted, I would never have known until I was here to experience it first hand.
As a Cambridge student, and not studying economics, I cannot comment on your subject-specific or Oxford questions. However, I really would encourage you to review the courses thoroughly and apply to the one which most suits you. Admissions statistics are just that - statistics. You shouldn't base your college, course or University choice solely on the statistics as to whether you're going to get in; if you do that, you may fluff an interview through the stress of knowing 7% of applicants get in, and not get a place you otherwise deserve. Do the stats let you know how many of those applicants were rejected outright because they did not meet some decent GCSE/A level standard, but people put an application in on a whim? If you're going to analyse the stats, do so carefully and objectively. They don't always tell the story you think they tell, and can and often are manipulated to the advantage of their publisher.
There are also many, many other excellent Universities out there if you do not get in. It will seem disappointing at the time, but all is not lost.