Is amoxicillin right for the treatment of boils?

No. Boils will frequently resolve with hot salt water soaks until they drain. Boils are usually caused by staphylococcus aureus. Over 90% of s.Aureus are resistant to amoxicillin. Dicloxicillin or Keflex would be effective against mssa. Mrsa is usually treated orally with septra/bactrim, Doxycycline or clindamycin.
No. No antibiotic is very effective against boils, which usually need to be opened and drained. But Amoxicillin would be particularly ineffective, since it doesn't treat staph, the most common cause of boils.