My advice would be to apply for what you want, not what you think you may/may not have the best chances of getting. Intel and IW are VERY different from SWO, so if you're not fully committed to being a SWO (or any other designator you list), don't list it at all when you apply.
I won't speculate on how competitive you might be, but I can tell you the type of people currently getting selected IW. A large percentage of fellow IW Junior Officers have masters degrees, although they are rarely technical. I'm not sure why it keeps getting put out that math and science is required for IW - it is surely preferred, and once you become IW you need to get up to speed with a LOT of technical knowledge very quickly, but most of the people who are currently getting selected (in my personal, relatively short, experience) have degrees in Foreign Affairs, History, etc. and usually speak another language (which is almost always useless as an IWO, but it just gives you an idea of the type of person they're looking for).