ive recently been reading on LED and all that junk, for my gun arm of my metroid costume.. and yes, ALL LED NEED A RESISTOR , you connect the resistor to the power supply (battery) and the LED to the resistor, this limits the flow of current, so you dont BLoW your LED out, if you dont know what kind of resistor to use, gimme a PM (of if i get a load of PMS ill post it) I have a site with a BUNCH of information on making LEDs work. (the resistor you need depends on your batteries you use, and the LED specifications, aka a white LED requires more power to work, and depending on how Bright you want the bloody thing depends on the Resistor your using ^_^ _)
increasing the voltage WILL make it brighter, but i doubt make it blink faster, AND increasing the voltage without a resistor is risky, itll blow, maybe not the first time, but quickly.
if you want to safely make it brighter and more volts, get the right resistor, i think the biggest baddest resistor around me is like 2 bucks, most are quarters and change though. (the 2 buck one is not for regular LEDs lol)
makin blink faster.. i dunno.. havnt read about Blinkin LED yet... a resistor just limits the direct flow of power from the batteries
**** NEVER CONNECT A LED DIRECTLY TO A BATTERY AS IT WILL SHORT IT OUT INSTANTLY*****
resistors, when used properly, produce a very minor amount of heat, something to consider when using in your helmet and stuff, if its close to your skin (rf arent, but say you wanted a custom light in your face) make sure your skin is away/covered/protected, or theres a gap and a lil fan. ( resistors shouldnt "overheat" and blow or anything, but a little air circulation never hurt anyone.. expecially in there helmets ^_^