请教几个问题。。

{:4_100:} {:4_85:} 各位牛人们。。小弟请教几个问题。。{:7_163:}

1.申了一个保底学校的PHD。。之前一个教授问了几个问题。。然后我回过去。。上午收到一个邮件：
I read your credentials. It seems to me that your test scores are
high and you have a high potential to be successful in computational
mathematics and physics. If I support your application, are you
planning to come to join ***** University? Please let me
know your current situation and thoughts.
这样我应该怎么说呢。。小弟还有18个学校没有结果呢。。但是又不想放弃这个。。{:7_165:} 太贪心了。。

2. NCSU给的金融数学的AD。。给了我个PDF的文件
意思就是录取了，然后要签个字，再email回去。。
最后一句是：I'd appreciate a reply at your earliest convenience. I hope that you will consider this offer favorably 没有deadline。。而且还要寄资产证明过去。。才发I20。。
如果填了YES的话，资产证明也寄过去。收到了I20。。还能反悔吗？？
{:7_204:} AD受这个签名的限制吗？

谢谢各位了~~