What do I need for my website?

I really need some help deciding what hosting plan is right for me. The initial question is Linux or Windows. Please help me decide what I need. I am also trying to figure out if I need php pages or asp pages. I am stumpted and need some direction.

Here is my info:

My website: www.want2sharenetwork.com

It is almost complete except for my issues that I need your answers to help me with.

I created the entire site so far in html I it is fine up to this point but now I need to do things that I can't do in html.

QUESTION # 1 : Do I need PHP or ASP for the following problems?

#1 I need users to register & create logon. I need an account # assigned to them when their login is created.
#2 I need them to record their name address telephone etc
#3 I need them to complete a survey
#4 I need them to have access to their bills & ability to pay their bills via Paly Pal Website Pro after they login using their registered account.

Here is the tricky part. After they complete all of this information. I need the data recorded into a database. I need the ability to pull that data, change it, & add additional data at any point.

I am hiring someone to do the pages for me in php but don't know if that is the right choice.

Is php script capable of doing all of the above tasks or do I need an interactive script like ASP?

The general idea is that I need to record all of this information and retrieve it and edit it at anytime.

I am trying to do what anyone who signs up for service or pays their bills through say a phone company website. ASP or PHP that is the question. If I get that question answered then I know what web host / hosting platform to choose?

Thanks for any help you can give.