Alan's answer is spot on.

Avoid javaScript or carefully follow best-practices so Google can crawl all content without reading javaScript. Alan is exactly right when he said: never count on Google crawling through your JavaScript to find content, but also never count on being able to hide anything from Google via JavaScript.

Whether you use PHP or not is not directly relevant. PHP is executed server-side, so Google never sees your PHP code and doesn't care. What matters is whether your programmer writes PHP code that will generate search friendly HTML code, url structure, etc.

Depending on what the pages are, I would let them get indexed so they can be ranked for any longtail keywords, then perhaps 301 redirect them to the main sale page. Or leave them up with a notice that product is no longer available but display related products.

Well, you're probably either getting more traffic and/or maybe you need to optimize your file sizes.

How much bandwidth have you used?

Usually images or videos are what gobbles up bandwidth. Are you hosting any large images, videos, or files?

Load time can be a server issue, a software/coding issue, and/or a filesize issue.

4GB of bandwidth in 4 days is a lot - that's how much my site that gets 30K+ uniques per month has used. Based on Alexa rank, it looks like your site doesn't get that much traffic? Have you had an uptick in traffic?

You can check page and file sizes at http://tools.pingdom.com/fpt/ That tool shows your homepage and associated files has a total size of 1MB. To use 4GB of bandwidth at that rate, you'd need ~4,000 pageviews.

You could run your top pages through that tool and see if any of the embedded images or other files are too large.

You could also check your log files to see if someone has embedded an image from your site, you're getting crawled by robots, etc.

Hope that helps!