If your assumption is correct, you want
df_rn <- df / rowSums(sqrt(df^2))
rowSums(df_rn^2)
[1] 1 1 1 1 1
so all rows are now normalized by their l2 (euclidean) lengths.
Not much can be said about plotting in 5d: it is impossible. Usually 2d (rarely - 3d) projections are drawn. The question of projection plane is open; it depends on what are you trying to show.