No, it's not true. You can use male forms for a woman (and then they take male adjectives), but in the same time Russian is slowly getting more and more female forms, although it's quite conservative in that.
As for the 'artist', the female form exists, «А́нна — хоро́шая худо́жница». The word «худо́жница» is in fact widespread, and I personally find the sentence with the female form much more natural. But it seems the course authors would disagree with me, since they used the male form as the default version.
We accept feminine forms, too. We just do not teach them because for the most part they do not translate well ("Ann is a female teacher?" Come again?) and do not add that much to the course. Every feminine form would add one more "person"-word to the course, which would make people-related skills much longer than necessary with questionable benefits.
As a result, we have them as secondary forms that sometimes appear or are accepted but are rarely forced upon the user.
So are they optional? In other languages I'm familiar with, besides English, masculine and feminine forms are largely mandatory. I understand what you mean about the forms cluttering up the course unnecessarily, but I'd like to know them. Are feminine suffixes always the same or are there more than one?
The names of most professions were originally masculine, so it usually works — moreover, many feminine words will have a distinctly informal sound. A masculine form will be written in the job posting or in a document saying what your position is.
The feminine forms are not optional with nationalities (in singular, of course).
More that one suffix exists, though, the relation between the masculine and the feminine suffix is rather predictable:
- учитель / учительница
- англичанин / англичанка
- американец/американка, испанец/испанка, китаец / китаянка
- канадец / канадка
(you can look it up on Russian Wikipedia in the country's or the settlement's description)
Amusingly enough, машинист is a train driver whereas is машинистка a typist.
In its literal sense it means a person creating works of visual art (usually by drawing or painting; sculpture is a different class, and photography is also excluded).
In a metaphorical sense it can also be applied to a person who is involved in what one may call "art".
Dash is required when both the subject and the predicate are nouns or nominal phrases. So, it is neccessary in the following cases:
- А́нна — изве́стная писа́тельница. 'Anna is a well-known writer.'
- А́нна — сестра́ Ило́ны. 'Anna is Ilona's sister.'
- А́нна — космона́втка. 'Anna an astronaut.'
But it's not required if the predicate is an adjective:
- А́нна изве́стная. 'Anna is well-known.'
- А́нна бога́тая и знамени́тая. 'Anna is rich and famous.'
It's not required when the subject is a pronoun, either:
- Она́ изве́стная писа́тельница. 'She is a famous writer.'
- Я сестра́ Ило́ны. 'I am Ilona's sister.'
- Ты космона́втка. 'You're a astronaut.' [said to a woman]
- Вы изве́стная. 'You're famous.' [said to a woman]
- Вы бога́тые и знамени́тые. 'You're rich and famous.' [said to several people]
It's not a mistake to put a dash in those sentences. But then the dash marks a real pause in speech, it adds emphasis:
- Я — изве́стная писа́тельница! Поду́мать то́лько! 'I am a famous writer! Unbelievable!'
Upd.: oh, I was too slow, this was answered already. xD
It is standard punctuation in "A is B" sentence when no explicit copula is present while A and B are both nouns. No dash is usually present in negative sentences of this kind or in questions.
Such conventions are not exactly grammar because you do not hear dashes and commas in speech.