questions on mechanics (Baldur's Gate: Enhanced Edition)

In BG a mage with specialization feature - enemies take -2 penalty to saving throw during casting to special sing - charnow of the wizard, fire arrows at the Summoner, etc. While the cleric, in which you can sadoulet such spices, their castes also belong to different schools - the question is, if gash necro-cleric, the cleric caste, too, will act the bonus or not?

Plus caste with the increase in damage from level caster - type touch of a vampire, after Douala there damage will grow or not - guess that wouldn't care, but suddenly, the level casthouse-growing - evil protagonist gets such a caste free and they damage just the same increases with increase in the active class, even if it is a thief.