I only looked quickly at the wiki for stats info and shit like that, it wasn't updated with half the stats actual effect though.
For stats:
Vitality = HP
Endurance = Stamina & Resists
Strength = Heavy weapon ATK and prerequisite for certain weapons
Skill (Dex) = Fast weapon ATK and prerequisite for certain weapons
Bloodtinge = Firearm & blood damage stat -- for firearms it applies mostly to Quicksilver bullets & is a prerequisite stat for equipment (iirc this also increases item discovery)
Arcane = Arcane ATK & prerequisite for equipment -- the arcane ATK applies to elemental damage types (i.e.: molotovs)
Other Stats:
Blood Echoes = new 'Souls' currency for buying levels/items
Insight = new version of 'Humanity' -- allows ringing of the bell for co-op/invasions
Other changes:
To initiate co-op also enables invasions via the Bell Maiden -- this isn't too different than going human in DS1/2
The 'Beast Mode' is rumored to start when the frenzy meter gets filled up by killing mobs (this can't be confirmed since online services aren't active yet), there are also items that change the rate of frenzy gain, etc.
Weapons have 3 Rune slots that have specific shapes -- this is how you add elemental damage types to weapons, etc. There are also bigger bonus runes that have drawbacks.
The starting class stat distribution (all start at level 10 except the Waste of Skin)
