Thermometer Design question.

So im trying to create a LED or LCD small digital thermometer. display size about .5 in H and 1-1.5 in L. And as thin as possible. 3 digit read out with possibly a two color back light. With 4 programmable buttons one to flip the direction of the display, one power, one alarm set ( to switch the color of the screen once reached ) as well as a button for C / F. I know there is a lot here but any direction you could send me in would help out a lot. Thanks! with a separated sensor about 7 inches from the display. Not really sure how to bring it all together so any help would be greatly appreciated.

I can go to Harbor Freight and buy a cheap Chinese thermometer like you describe for ~$10US. Why would I waste my time building one?

I'm not really sure I understand everything you're talking about, but if you want to make your own thermometer try looking into a simple ADC with a display driver built in. Some good ones are the ICL7106 (LCD version), ICL7107 (LED version), and the ICL7129. Those are just a few ideas.