三封回复UCB, Harvard, Cornell, 求问是否需要跟进以及如何跟进？(给米)

由于CV，Robotics这些领域竞争实在是太激烈了，所以lz对套磁的兴趣缺缺，以为意义不大。所以只对几个特别感兴趣的组稀稀拉拉地发了十来封陶瓷邮件，然后稀稀拉拉地收到以下三封回复。

第一封：
Professor in Harvard

Hi Yiyou,
Thanks for your interest in joining my group. At this stage we are collecting applications through the Harvard/SEAS graduate admissions process. Please make sure you get your reference letters in on time. Admission decisions are being sent out later in the spring. Meanwhile I will keep an eye out for your application.
Best,

XXX

第二封：
Assistant Professor in UCB

Hi Yiyou,Please do apply to the Berkeley PhD program and mention me in your application.
Thank you!
XXX

第三封：
Professor in Cornell
Hello,
Thank you for contacting me. Your record looks strong. But admissions in Cornell are not done by a professor. A committee decides who is admitted to the department. You should apply to the department this year if you are interested. Applications to Cornell are very competitive: a good application has extremely positive letters of recommendation, a strong statement of purpose, and the usual strong grades/tests. Research experience is also highly valued such as papers in known international conferences, so please include that information. There are several faculty who could be a match for you, so specify the people you might want to work with in your statement. Please contact Becky Stewart (1point3acres.com) for more information about our PhD program.
Best of luck,
Prof. XXX

真心求大神分析，
1、这些回复中分别是几分客套几分认真？
2、是否需要回复？如果不回复是否不礼貌？要是回复需要说些啥？