At 2nd level, a half-elf paragon gains new spells per day (and spells known, if applicable) as if she had also gained a level in a spellcasting class she belonged to before adding the level. She does not, however, gain any other benefit a character of that class would have gained (bonus metamagic or item creation feats, bard or assassin abilities, and so on). This essentially means that she adds the level of half-elf paragon to the level in the spellcasting class, then determines spells per day, spells known, and caster level accordingly.
