"1. Special variables seems really like a take it or leave it idea. I'm really not convinced that keeping these as explicit arguments of a function are a bad idea. I really like the ability to reason about a function by simply knowing its arguments (including the mplicit self/this)."

Sometimes it is nice to influence the entire call stack. The canonical example of this is probably re-directing "system out." Special variables provide a nice solution to the problem of making all the printlns in a call stack go to a file instead of the console or REPL, for example. That would be really awkward if you had to chain the System Out variable through all the calls.