The Uno has 6 analog inputs (ADC) and can "talk" via USB to a PC / Mac / whatever using serial communications. You can attach shields as you said to have an SD card and RTC.
SD card support, and RTC, just plug it in. Then add your sensors.
How should I proceed?
It's fun, but I think you will have to learn some programming. There are various books and online tutorials that should smooth your path in that direction.