How can I convert an executable to a format Android phones can read?

Q. Most Android applications are written in Java, but I will use something else... I have no trouble of making the EXE file but can someone please tell me how to convert it to a file Android can read?

A. Android system does not understand PE format. so called windows exe files are in this format (PE stands for Portable Executable but it is not so portable after all!). likely Android executable frmat is ELF, a well-known widely used (among several systems) "codes container".
moreover, the code into windows executable files is for x86 processors (or for CLR, not JVM), and Android hardware for sure has no x86 processors and afaik no x86-opcode compatible processor too.

so basically, it's nonsense "converting" an exe (specific format, specific system, specific machine code for specific processor, specific library bindings) into "a file Android can 'read'" (oh, as passive data you can transfer the exe to android as it is, but forget it can run it or even "see" that there's code inside! just data to it!)

What is the difference between Android Operating System and an actual Droid?

Q. Obviously, a Droid probably uses the Android OS, but I know that some phones aren't actually Droids, but use the Android OS. So, what is the difference in what I am going to get with each product. Is either better than the other. I am specifically looking at an LG Optimus S, but didn't know how this would differ from a Droid.

A. Actually there is no different when each one has Android system. Droid is only fror CDMA.

How has Android taken over as the Smartphone OS of choice?

Q. Android offers you more for your money, there are more varieties than iOS. People like variety. With an iPhone you cannot remove the battery unless you are a Mechanic.

A. Android phones are cheaper than iPhone. Latest Android flagship phones with their quad core chipsets will blast iPhone into the waters. Android is an open os while ios is closed. Android offers freedom of choice which iPhone can't. Also they have replaceable batteries and sd card slot, nfc, better camera and battery rating. Anyone can root it overclock it and install custom roms according to their preference. It's very east to backup contacts including social networks by syncing them to your email and can be easily retrieved.