Yes. Yes you can!
No. Fissure sealants are on the biting surfaces of teeth and brackets are bonded to to smooth surface (sides) of the tooth.
Yes. Usually brackers (braces) are placed on the cheek surface of the teeth wile sealants are placeed on the top surface of the teeth. On the lower molars there is a cheek surface fissure to which brackets can be attached if it is sealed. The sealant can always be redone if necessary after treatment. The bracket bonding material and the sealant are very similar adhesives. Read more...