a) More items (and items diversity); I just love finding treasures; but a bit of diversity could help here
this I can agree with

The early game toned down just a little - not too sure of a good way to address this issue; maybe placement not in a corner or something.
my experiences are different - if you start in a good spot (=at least 3/4/2), the early critters are a cakewalk, and with leveling as quick as it is, you breeze through the beginning. What I'd do really is toughen the trash mobs like mites, darklings, black widows and bear cubs.
c) Late game needs to be a bit tougher; the last game I won via quest; but it only took 3 (or 4) rounds to kill the critter; and I only took 10 damage.
This is of course true. High-end levelling should be much, much slower, while the effects of armor lessened. And the big baddies toughened, too.