Ella la compra. I don't think there are two object pronouns that can be used in this one sentence, so I would assume that the second pronoun was for another sentence.
For 1-6, all you have to do is conjugate the words by taking away the -ar at the end of the infinitive and adding the designated ending.
1. cantar, canto, cantas, canta, cantamos, cantan
2. preguntar, pregunto, preguntas, pregunta, preguntamos, preguntan
3. contestar, contesto, contestas, contesta, contestamos, contestan
4. practicar, practico, practicas, practica, practicamos, practican
5. desear, deseo, deseas, desea, deseamos, desean
6. llevar, llevo, llevas, lleva, llevamos, llevan
section two conjugate the infinitive like before, with the subject from the sentence
1. viajan
2. hablamos
3. llegan
4.dibujo
5. compra
6. regresan
7. termina (i think)
8. buscas
The question asks whether you would like to go to a concert or would like to listen to music.
you can write:
Yo quiero ir a un concierto
or:
Yo prefiero escuchar la música en casa.