Osp, USp, SU(,) and PSU I would be glad if someone can give me some (hopefully easy to understand!) references for learning about these groups Osp, USp and PSU and their representations. 
I run into these mostly while studying about supersymmetry and I wonder if PSU groups are the same as what are called ``supergroups".   
I frequently run into $Osp(3\vert4)$, $USp(2N)$, $PSU(2,2\vert 4)$, $SU(2,2)$ and $SU(2\vert 4)$. 
(I don't understand this notation of having a "$\vert$" and I don't know the definition of any of these groups) 
Some of the concepts about them that I face are,


*

*The commuting subalgebra of the lie algebra of $SU(2,2,\vert m)$ is that of $SU(2,1\vert m-1)$. The generators of $SU(2,1\vert m-1)$ are related to those of $SU(2,2,\vert m)$ via some "obvious reduction". I don't know what that means. 

*The "bosonic subgroup" of $SU(2,1\vert m-1)$ is apparently $SU(2,1) \times U(m-1)$. I wonder what this means.

*The supersymmetry generators are supposed to transform as "bifundamentals"  under the bosonic subalgebra of $SU(2,2)$ and $SU(m)$. (I don't know what is a "bifundamental") 
I am very confused about these concepts and would be grateful if someone one help traverse this subject.    

Supergroups are a little tricky. It may be useful to learn about the corresponding Lie superalgebras instead. A possible place to start with learning the basics and notation is Kac's article, "A sketch of Lie superalgebra theory":
http://projecteuclid.org/euclid.cmp/1103900590
In particular, you may be interested in the section on p.58 on real Lie superalgebras where you'll find the lowercase (Lie superalgebra) versions of what you want.
