This is a really broad question, so it's hard to be specific. But... you need to start reading Data sheets.
Not everything you interface with will require a pre-built library. In fact, needing a library should be uncommon when just starting out.
Most work is done with the DIGITAL pins and the Arduino is what is called TTL Level Compatible. This means that parts that you interface should be driven by 5 volts.
Except from WIKI:
All standardized common TTL circuits operate with a 5-volt power supply. A TTL input signal is defined as "low" when between 0 V and 0.8 V with respect to the ground terminal, and "high" when between 2.2 V and 5 V11. TTL outputs are typically restricted to narrower limits of between 0 V and 0.4 V for a "low" and between 2.6 V and 5 V for a "high", providing 0.4V of noise immunity
This also means that the Analog pins operate at from 0 volts to 5 volts. 5 Volts should not be exceeded.
Knowing the TTL compatability and reading Data Sheets should help answer your questions about parts.
So... if you buy a 3.3V part... you might need to do some "level" shifting. something to keep in mind.