COS = Class Of Service = bonus miles for flying in First (or, indeed, business). Thus 200% is better than 50%. If you look under the help menu on the top right, there's a glossary which may help you begin to find your way around!

The problem here is that you don't earn status on an award ticket, but you'll need to earn the miles, so your best way of getting into the premium cabins AND earn status is through upgrade awards.
What kind of destinations are you interested in and are you prepared to transfer? bmi have a very limited network of European destinations - beyond that, with *A (Star Alliance) you're limited to partner destinations (of which there are quite a few - Lufthansa, SAS, Austrian, LOT and Swiss). The best route network for direct European flights from London is BA which would mean One World and partner you up with Qantas. But we're a little late for that, now you've bought your Singapore flights.
I am prepared to stand corrected on this, but I believe it's Air Canada with *G (Star Gold) at 35,000 miles within a calendar year from a standing start. bmi isn't much higher at 38K, BUT you need to earn silver first at 16K, whereupon you get reset so actually requiring 54K from a standing start. However you need to check the other vagaries of the two FFPs such as earning rates (you may not get 100% miles on discount economy fares, for example).
With very limited exceptions, none of which apply here, you actually need to flight to get status miles (which earn you your Gold). The credit cards (and hotels, and car hires, and all the rest of it) only give you award miles (which you can spend on flights).