IoN breakdown:
mounted characters and their mounts can
not regain wounds through IoN (this means the TG, Zombie Dragon, corpsecart or Abyssal Terror)
characters in units can
not regain wounds through IoN, only the unit can (so a character on foot or on horseback in a unit)
infantry regains casterlvl+1d6 (skeletons, graveguard)
zombies regain casterlvl+2d6 (zombies

)
Other trooptypes regain casterlvl+1 (CryptHorrors, Blackknights, corpsecart, batswarm)
ethereal regain 1 max (spirit host, hexwraith)
vampiric regain 1 max (Vargheists, Bloodknights)
large targets regain 1 max (Terrorgheist, Mortis Engine)
-- basically, Vampiric, Ethereal, Large Target or when mounted overrule the normal 'Other Troop Types' resolution for the spell and can only be healed 1 wound by IoN or not at all. The lore attribute can obviously only land on a model with multiple wounds.
As to your original question: If you 'Raise Dead' skeletons, you will need 'Master of the Dead' to increase that new unit of skeletons beyond their starting size. (definately not the best of choices since that unit comes without commandgroup and can only be increased with casterlvl+1d6, resulting often in a meager unit. I think any
VC player wonders why that version of 'Raise Dead' even exists)