This was obviously a long time ago, given the English. The character seems to be upset and he finds this loss to be a great one. He clearly loves this girl and he thinks losing her will be a tragedy. He is calling the girl the 'sweetest flower' and the 'untimely frost' is her death that happened too soon, with her being so young.
A parallel structure means that the same form of the word is used in each part of the sentence. So the correct answer is 'I look forward to visiting Phoenix and to meet Rachel'. For this sentence to be correct, it would need to say 'I look forward to visiting Phoenix and meeting Rachel'.
