If the conditions of probation prohibit being near alcohol, well, that answers that question.
As for performers being 18 or under, that depends on the license type of the premises. Are we talking about a bar? A restaurant?
In general, under 18 will not be permitted. 18 and over, maybe ....
25663. (a) Except as provided in subdivision (c), no licensee that
sells or serves alcoholic beverages for consumption on the premises
shall employ any person under 21 years of age for the purpose of
preparing or serving alcoholic beverages. Every person who employs or
uses the services of any person under the age of 21 years in or on
that portion of any premises, during business hours, which are
primarily designed and used for the sale and service of alcoholic
beverages for consumption on the premises is guilty of a misdemeanor.
(b) Any off-sale licensee who employs or uses the services of any
person under the age of 18 years for the sale of alcoholic beverages
shall be subject to suspension or revocation of his or her license,
except that a person under the age of 18 years may be employed or
used for those purposes if that person is under the continuous
supervision of a person 21 years of age or older.
(c) Any person between 18 and 21 years of age employed in any bona
fide public eating place, as defined in Sections 23038 and 23038.1,
which is licensed for the on-sale of alcoholic beverages, may serve
alcoholic beverages to consumers only under the following
circumstances: such service occurs in an area primarily designed and
used for the sale and service of food for consumption on the
premises; and the primary duties of the employee shall be the service
of meals to guests, with the service of alcoholic beverages being
incidental to such duties. For purposes of this subdivision, "serve"
or "service" includes the delivery, presentation, opening, or pouring
of an alcoholic beverage.
25663.5. Notwithstanding Section 25663 or any other provision of
law, persons 18 to 21 years of age may be employed as musicians, for
entertainment purposes only, during business hours on premises which
are primarily designed and used for the sale and service of alcoholic
beverages for consumption on the premises, if live acts,
demonstrations, or exhibitions which involve the exposure of the
private parts or buttocks of any participant or the breasts of any
female participant are not allowed on such premises. However, the
area of such employment shall be limited to a portion of the premises
that is restricted to the use exclusively of musicians or
entertainers in the performance of their functions, and no alcoholic
beverages shall be sold, served, consumed, or taken into that area.