Can I use an ATmega328P without Arduino, just using it in a breadboard for projects?
I'm basically self promoting here but hopefully it'll help.
I actually made a tutorial video that uses the ATmega328P and Atmel Studio 6 to blink an LED wired to the chip.
The video shows the circuit piece by piece. If you go into the description, there's code, a Schematic and a BOM to help you get started. There's some extra code as well for the ADC stuff. Unfortunately I didn't do anything with an LCD interface.
Blink Tutorial Video
And here's a video that shows the ADC working:
ADC ATmega328P
I realize this doesn't answer all your questions, but at least this might help you get started.