several questions regarding dashlights and 5sfe leak

[DAT RICE]

hi, i replaced my turn stalk signal assembly and put everything back together but now my airbag light is on. I believe that's normal but how do i reset it now? I'm confused with all the reset methods.

Also, my e-brake light is on. Does it do anything else besides detect e-brake? If not then my brake switch is messed up right? How do i fix that? This started happening when one night my brakes were very sloshy. Next morning,i checked and i had low fluid in the resevoir. Idk why but the brake leak disapeared. This is critical, it may come again.

3: I have an oil leak, that involves the left side of the engine. It leaks onto the belt so the oil winds up around that area and onto the hood. I wanna know what seals to buy.

4: My 5sfe is around %60 percent louder than my friends. The noise is from the engine itself, I read it could be a bad waterpump bearing. Any ideas? I'll examine the sound more closer tommorrow.