When you use $$img{...}, what does using two $'s mean...does that signify that you are using an array of hashes rather than just a simple array

Yes and no. An array of hashes are really an array of references to hashes. Therefore when you fetch something from the array, you get a hash reference back.
To actually use the hash, you then have to de-reference it. There are two syntactic ways of doing that $reference->{} or $$reference{}
I like the latter best, mostly because its shorter and because it is coloured yellow in emacs...
Read the perlref manpage

T I M T O W T D I