Can benzene ring be the part of a acyl group
Yes, acyl groups can be derived from all kinds of oxoacids.

According to the Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995), acyl groups are defined as follows:


  Groups formed by removing one or more hydroxy groups from oxoacids that have the general structure $\ce{R_$k$E(=O)_l(OH)_m}\ (l\neq0)$, and replacement analogues of such acyl groups. (…) In organic chemistry an unspecified acyl group is commonly a carboxylic acyl group.


Especially concerning acyl groups derived from carboxylic acids in organic chemistry, the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) defines:


  Carboacyl groups are $\ce{R-CO-{}}$, $\ce{-OC-R-CO-{}}$, or $\ce{-OC-R-[R'-CO-]_$x$-R''-CO-{}}$ groups and their functional replacement analogues, where $\ce{R}$, $\ce{R'}$, and $\ce{R''}$ are chains, rings, or ring systems, derived from carboxylic acids by the removal of the hydroxy group from each carboxylic acid group that is expressed by the suffix, and $x = 1 ,2,3$, etc.
  (…)


In particular, benzoyl is explicitly mentioned as an example for an acyl group.