Where did you find that 2.7m number? The most recent data is the Credit Suisse 2015 set, which you can see here:
https://www.credit-suisse.com/uk/en/about-us/research/resear...
They put the 1% line at $760k, and that's net worth: include the value of your home, subtract your debts.
I'm pretty unhappy about this oxfam article. It talks about "the richest 1%" and "the billionaires" alongside each other as if these groups were even remotely similar. This is furthering the myth of some kind of group of "shady rich people" who are behind the global financial conspiracy. Reality check: if you're reading this, you're almost certainly in the top 10% ($68,845 in total assets). According to the same data set, the median wealth in the US is $50k, so about half the population is in the top ten percent. You are the rich people this article is talking about.
Comparing the "richest 80 billionaires" to the bottom 50% is similarly misleading, because the bottom 50% has about 0.5% of the global wealth (which I think roughly answers your question about the top 0.001%). If you lined up the top 80 billionaires, shot them all, and redistributed all their wealth to the bottom 50%, then those people would still be in extreme poverty.
There are serious global wealth inequality problems, and this oxfam article doesn't really talk about them at all, and instead tries to perpetuate a popular meme. I strongly suggest that people skip it and read the Credit Suisse report instead - the data tells a much more interesting story.
Here are the numbers which the oxfam article doesn't mention, and should:
85.65% of the global wealth is held by the top 10% of the population, which is 477m people, of which 113m are in the US, with second place going to Japan at 58m.
32.3% of global wealth is held by the middle class (defined as $50k to $500k wealth); 92.4% is held by the middle class or above. 37% is in the US. Africa, India, and Latin America together represent about 4%.