Suggestions on adding eCart to previously developed html site...

I'm the first one to admit that when it comes to web design, I'm back in the 90's. I have to start doing it again because as a computer consultant, the only business I'm getting lately is web design! So please bear with me as I'm sure my question is really quite a simple one.

And to make this harder, this is for a charity and I'm doing this pro bono but they need it up for their charity event this weekend! Because at this once-a-year event, the website donate feature will be announced so people can go to the website and donate online.

My system tools:

• WebAssist Super Suite (latest version)
  
• Dreamweaver CS3
  
• PHP 5.2.9-1
  
• mySQL 5.0.77 (64-bit Windows)
  
• IIS 7.0.6 (I'm thinking of canning IIS and changing to Apache, should I?)
  
• Windows Vista Home Premium 64-bit

Web host:

• GoDaddy.com
  
• Linux
  
• PHP 5.2.8
  
• MySQL 5.0 (I'm thinking this is gonna be a 32-bit db)
  
• Chase Paymentech eCommerce merchant account w/ Orbital

I purchased a template from an online template factory to start the site a month ago. It incorporates some extremely basic CSS style sheets but no template. So each page has to be changed manually with each site update. I plan on re-developing the site but I don't have the time or expertise to do that right now.

Anyhow, what I am tasked to do is to add a simple shopping cart to accept donations in preset amounts and have a radio-button field for a user submitted amount. (i.e. $5, $10, $25, Other). If the user clicks the Other button, then they will have to put in a valid amount (no less than $5 and no more than $500 as they want all large donations to go through the office for some reason). I also need to have a simple checkbox validation field that they have to check to proceed. All the information must be captured in a database for future needs. We need to use this stored information for upcoming invitations to events, end of year tax reporting (they get a tax write-off for the donation), etc. And finally, we would like to send a thank you email and letter to the contributor. The letter will be done manually each month based on the database information. But the email should be automatic through the Universal Email program which I haven't learned yet...

And to complicate matters, they have asked me to add a recurring option. So that if they cannot afford to donate much, they can check an amount and have that charge the contributor's credit card no a weekly, bi-weekly or monthly basis. Thankfully, this doesn't have to be ready by this weekend. (I have no clue how to even begin this one!)

What I need to figure out is where I start. Yesterday, I just figured out how to install a test server with PHP, MySQL, & IIS on my computer. It was a nightmare to get the 32 bit versions to cooperate with the 64 bit versions. Then, I had a horrible time re-installing my MySQL because the service got corrupted due to improper shutdown. After 4 hours (ashamedly, I am not exaggerating) I got it all done and was able to begin the eCart Getting Started Guide. That all made sense to me and worked nicely. So now, I need to apply what I've learned to practical application.

In short:

• Do I need to redevelop my whole .html site to be .php or can I just have (for now) the shopping cart page .php?
  
• What is the quickest way to get the databases I need? Do I have to manually develop all of them or are there pre-existing databases out there to use and just add your items?
  
  • Can I just reconfigure the WebAssist blue_sky_music database easily and use a T_SQL statement of some sort to recreate a charity_cart database? (GoDaddy doesn't let you copy databases from what I see, you have to manually create it on there site or use a T-SQL statement to create it)

  
  

• Is it easy to add a different Payment Gateway to the eCart Wizard? Or is there a simple work-around for this? (I submitted a support ticket for this last night)
  
• Is there something else that I am missing?

I appreciate all of your help. I am really trying to learn all of this and I'm getting a crash course, which I like, but it is stressful due to the client's deadline.