hardware interfacing and data logging
For data logging, you can use an SD card. The Uno only has a few KB memory and is non volatile, and EEPROM space is even less. There are plenty examples how to store data to an SD card.

You can check if you can read it with an analog port. If that's possible, you need just one command to read the data.

The only disadvantage I see, is you need more or less current depending on the data. If you use a battery operated device, depending on the data the battery goes empty faster or slower.

UPDATE

How to measure current with an ADC converter: You measure the voltage drop across a resistor in series with the load - simple ohms law, a 1 ohm resistor will drop 1V for every amp of current.
You have to take care about the wattage of the resistor possibly (using P = U * I).

If you search for 'measure current with ADC converter' you find plenty of links.