see above

Not counting there previous lives skeletons can be any age and wont die of old age until the magic or curse keeping them alive ends

you can see in darkness up to 60 feet, both magical and non magical. you cant discern colour

if a limb is severed you can replace it with a relevant bone as an action

your creature type is undead and you aren't affected by normal healing spells

As an action you may collapse into a non-moving skeleton. You are undistinguishable from another skeleton and whilst in this state you are prone and your movement is 0.

immune to disease and poison and resistance to poison damage, don't need to eat or breath. instead of sleeping deactivate for at least 4 hours a day. you do not dream and are fully aware of your surrounding.

can cast spells using a spell slot higher once per short rest. if you do roll d10, on a roll of one you take psychic damage equal to four times the new spell slot level and the spell fails (Wild magic if dm is mean).