Build My Own Mobile Device

Hey people!! im going to be building a mobile device(i bet your thinking this guy is nuts)...will im going to pursue a dream and i hope your willing to help. (if your awsome you will). will here's how it is, im a developer looking for a project to work on such as(mobile device not a phone)
the kind of mobile device im planning on building is something like the ipod touch ..but different(ima have more details on the mobile device later) but im here just to ask a couple of question like: what kind of os should i use? What kind of processor do a mobile device need to play mp3, and mp4 files?(including wallpaper with very detailed graffics such as a ipod touch, and game capaditble) what kind of language should i use for development/and what programs(such as photoshop)should i use to store,develop video files and pictures on to the mobile device.

will thats all the question i have for now ill post more later...thanks in advance.

im a ready to gooo.