Hi,
for some ideas on how to do things, have a look at the following site: http://roguelikedevelopment.org/development/.

It contains lots of articles on many different aspects of rogulike development. some of it is c++ based but the ideas still stand.

Also I'd second XDG's comment about placing the increment in brackets.

Instead of

elsif ($dungeon[$start] eq '#' && $dungeon[$start] + 1 eq '#'
[download]

try

elsif ($dungeon[$start] eq '#' && $dungeon[$start+1]  eq '#'
[download]

Also see cpan for some modules you might find handy,
Games-Lineofsight
Games-Maze
Games-Dice


Hope this helps.
Displeaser