When I hooks up LEDS to the GPIO, and switched the Pi on, I noticed that pins SDA, SCL, CE0 and CE1 all turned on without me programming them. Are they always automatically on? Or are they meant for input only.
The answer depend in part on how you connect them. You should always provide this kind of information when asking a question (to save people having to ask).
I assume you have LED connected to Gnd. Pin 3,5 are intended for use with I²C and have 1.8k pullup to 3.3V.
Pin 24,26 are normal pins, configured as input by default. They are often used in conjunction with
SPI, so again it depend on what you have configured.