the 194 corner bulbs are not a problem if changed...

If you put 1157's in the brake lights, your "brake light" idiot light will come on.

You can put them in your turn signals, but you need a variable load flasher to make them flash at the proper speed.

They bright/dim "filaments" tend to not be as noticable as with a regular incandescent bulb... but LED's are rated to last about 100,000 hours... which basically means they should out-last your car.