How to Integrate eCart5 with PayPal

Ok, so you didn't say that I had to download the PayPal eCommerce Tookit, so I'm assuming I don't.

Here's what I don't understand...
You say that I shouldn't bypass the Checkout.php page, however, I don't want to use the PayPal Express Checkout button, and I don't need my customers to enter their financial info (because they'll be asked for it on the PayPal Payment Login Page that I'm expecting to display next...see attachment).

Which leads me to the WA Checkout wizard...there is a "Quick Demo" link under the PayPal Website Payments Standards selection. Per the demo, there are 2 ways to integrate...1) Use PayPal buttons (don't want to do) or 2) Use existing shopping cart and only use PayPal as the transaction processor (this is what I want). The demo states "All your customer has to do is click the Checkout button from your cart, pay for their items in PayPal, and return back to your site." The demo shows your own shopping cart with an orange (non-PayPal standard) CHECKOUT button, then the PayPal Payment Login page. There are no extraneous steps in between, which is what I like. How can I achieve this if you say I shouldn't bypass the Checkout.php page?

Also, I now understand that I would only need API credentials if I wanted to use the PayPal Express Checkout.

Additionally, I must have something incorrectly setup in the wizard or elsewhere because when I navigate through the checkout pages (first checkout, then order confirmation) I'm taken to the PayPal Home page (see 2nd & 3rd attachments) and prompted to login (instead of the PayPal Payment Login page that I'm expecting to see). I log into the PayPal Home Page, to see if I'll be redirected but I'm not. I have made some Profile settings in PayPal, hoping that it will recognize my saved settings and navigate me like a customer, but still no luck. ALSO, I have abandoned the idea of using the PayPal Testing server...so I'm entering my LIVE member info in the wizard and have de-selected the "using Sandbox" checkbox in the wizard.

I have entered my full live PayPal business id in the member id field of the Checkout wizard, just the email portion of my business id, just the business name portion of my business id AND just the merchant id supplied by PayPal on separate occassions to no avail....I still get navigated to the PayPal home page instead of a Payment page.

I also tried navigating through the checkout pages using a different computer, hoping it wouldn't recognize me....and it didn't, but still took me to the PayPal Home page. Thanks!