There's currently a Google summer of code project implementing overloaded record fields (http://www.google-melange.com/gsoc/project/google/gsoc2013/adamgundry/2

There's currently a Google summer of code project implementing overloaded record fields (http://www.google-melange.com/gsoc/project/google/gsoc2013/adamgundry/23001 http://www.google-melange.com/gsoc/project/google/gsoc2013/a...) - which should kinda solve problem 2. You still wouldn't be able to define a field `map` for the same reasons you stated, but you would be able to have multiple record types sharing the same field names.