All Lisps have "special forms" which are evaluated uniquely and differently from function application and are therefore reserved words by another name. For example, Clojure has def, if, do, let, var, quote, fn, loop, recur, throw, try, monitor-enter, monitor-exit, dot, new and set!.
Yes, but the special forms are not distinguishable from user defined macros --- and some Lisp-implemantations special forms are another implementations macros. E.g. you can choose to make `if' a macro that expands to `cond' or vice versa. I do not know whether you are allowed to shadow the name of special-forms.
If you count reserved tokens, I guess Lisp reserves parentheses and whitespace?
Not if you are using Common Lisp. There you can install reader-macros that act on characters in the input-stream. (Most macros act on stuff in the already parsed syntrax tree.) Forth is also a remarkably flexible language in this regard. Matthias.