Foolish questions on earning experience

[Saulot]

Experience is accrued slowly simply by existing.
Experience is given for entering battle.
Experience is given for killing.
Experience is given for dying. (I kid you not... apparently it's quite an experience)

5 stars and one heroic ability is the max.

As for all the abilities, discovery is part of the fun. (To be honest, there are many and it's hard to remember all of them)

But a not so comprehensive list includes:
Heroic Quickness
Heroic Precision
Heroic Strength
Heroic Agility
Heroic Toughness
Heroic Endurance
Heroic Stupidity
Unequaled Obesity
Iron Will
Valor
Lightning Reflexes
Heroic Battle Prowess
Third Eye
Battle Bellow
Legendary Cruelty
Awesome Presence

Edit:
Oh and this might be useful
Effects of increased experience (non-cumulative)

XP 1 (15pts)
Att +1
Def +1
Prec +1
Mrl +1

XP 2 (50pts.)
Att +2
Def +2
Prec +2
Mrl +2

XP 3 (100pts)
Att +3
Def +3
Prec +3
Mrl +3
Str +1

XP 4 (200pts)
Att +4
Def +4
Prec +4
Mrl +4
Str +1
Enc -1
HP +2

XP 5 (400pts)
Att +5
Def +5
Prec +5
Mrl +5
Str +2
Enc -1
HP +2