We have been trying to help, and you are free to do what you wish with your bike its yours. It may not be as simple as you think. Some shifters are indexed so it expect the chain rings to be specific distances apart. There was a time years ago you probably could have easily pulled this off on an old friction shift system, but back then you had to feel the shift and how many gears you wanted to go. There were no clicks. Now with what is known as a trigger shift, you have three distinct positions. If you adjust the system to use numbers 1 and 2 for your chainrings, what happens when you accidentally go to number 3??? I see no way to adjust this without a new shifter.
A 7 speed chain has different spacing from 8 and 8 from 9, so those are all different because the chain is different. The link sizes are different. I think 9/10 are the same, but I rarely deal with these.
Then you have to consider the front derailleur is now often designed to be used with a given shifter and not all shifters are compatible with all derailleurs. If you go to a 2 chain ring shifter, that may or may not work with your current front derailleur. The only ones that really know are people like Hack that are reviewing the stuff all the time, and bicycle mechanics that fix them day in and day out. Its always changing. Who knows best?? That local bike shop. I have a performance bike near me, but not sure about where you are. Go talk to them or the bike shop near you. The only real way is to have a mechanic look at what you have and tell them what you want to do. They should know if it will work.
You have to remember that customizing will only do so much. Bikes are built for a purpose. You won't make a road bike ready for the x games any more than you are going to ride the tour on a BMX and win. Most everything in life is a compromise. With enough money you can do most anything to any bike. You can also create a bill that will easily exceed what it would cost to buy a bike that is designed and built for the purpose of what you are trying to customize to achieve.
Hack and sprocket girl gave you good advise. Most local bike mechanics would as well. Everyone here has tried to see that you enjoy your ride and have been genuinely concerned about your safety. My advise again would be to ride what you have for a while and gain some experience and fitness. Right now that would probably do more for your bikes performance than any thing you can buy. As your experience grows you may want a different bike, or you may want to make changes, but go slow. Think twice. Then think twice again. Most of the time a bike is the way it is for a reason and there was probably a reason it wasn't built that way in the first place. Most cyclist want to help other cyclists. What you do with that help is up to you.