To read a Landsat 8 product use the ReadLandsat8 function:
library(rLandsat8)
setwd("~/Downloads")
product <- "LC82040322013219LGN00"
l <- ReadLandsat8(product)
Access the product metadata
product.metadata <- l$metadata
product.metadata is an R list containing the Landsat 8 product metadata.
To access a metadata field value, e.g. the wrs path, do:
product.metadata$wrs_path
To access a band:
blue <- l$band$blue