Manage inactive pages for better optimization

I have an eCommerce site where I sell a lot of unique products. I have more than 500 products and most of them only exist in single quantity.
So when items get sold, I deactivate them but still keep them in the database in case I manage to get the items back, which sometimes happens after few months. Then I reactive the product.

This apparently is giving a lot of "page not found errors" on search engine and I have been advised
to redirect the inactive pages.
But is this the best thing to do? Should I keep inactive items in my database and redirect them to some other page? Or should I just
delete them? I don’t want my database to increase continuously.

Any advice or solution?

Content or Back Links

Hi Friends,
For an e-commerce site, what does google give more priority to, a good content or back links?

For example,
Site A: Lots of relevant content and information about the site and the products sold on the site. But no back-links at all.
Site B: Lots of back-links but very few to none content on the site.

For Google, which site wins?

Very Poor Conversion Rate

As the title indicates, my e-commerce site has a very poor conversion rate. I assigned CPC Adwords and Facebook campaign management to the seo expert that I worked with in the past
for this holiday season. I was hoping to boost my sales through these ads campaigns, but ended up
spending as much as I made from the ads on both Adwords and Facebook.
The seo guy was very disappointed and surprised to say the least. My website had a conversion rate of 0.37% :( :(

So I am here asking your opinion about why the rate is so poor. Does it have to do the website’s design/layout,
color, product images, call-to-action button issue etc. What could it be?
Here’s my site:

Tons of visitors but no sale

I have a CMS page on my ecommerce site that is mainly informative. It is ranked very well on google and brings in a lot of visitors.
Out of 3000 unique visitors per month, this page alone gets close to 1800 of them. But I am having a serious problem converting these readers into buyers.
Are there any effective tricks and tips to achieve this?
One of the things I though of was to have a pop-up appear after few seconds offering a discount for a purchase. But this to me looks very commercial and can put off readers.

Can you guys please share your opinion?

SEO expert. Risks and Benifits

Hi guys,
I was wondering how much risk we run into by letting our SEO expert access our server and back-panel of e-commcerce shop.
He/she will have access to our account information, monthly earrings and other private information.
Can he/she take undue advantage of it?
Has anyone encountered some unpleasant experience with their SEO expert? Or if you are a SEO expert,
have you or do you see ways to blackmail and take advantage of your clients?

Please share your opinions.

SEO expert’s bargaining chip

When one engages a SEO expert on his/her e-commerce site, the SEO expert demands a full access to google analytics account in order to do his job properly. This is also his way for generating traffic reports to send it to the client. However, the access to google analytics also gives the SEO expert access to the accounts of the company. He has thus a full knowledge of how much revenue was generated in a month by the company. This knowledge then gives him a power to negotiate his SEO fees frequently with the company. He will start to think that the more revenue the company makes, the more his SEO fees should be. But any given company can only increase the pay of a SEO expert to a certain level. If the company’s revenue doubles in four months after hiring the SEO expert, that should not mean that the SEO expert’s fees should also double. The increase in the revenue could be due to other factors not related to the SEO experts work.
So what do you guys think? Is it fair for the SEO expert to demand increase in his fees because the company’s revenue has gone up?

Back link and google

I have an old website which only contains information and a new website on which I sell some products. The old site is ranked quite well on google. So I was thinking of adding some pictures of my products on the old site and linking them to my new site. There will be around 80-100 product pictures. Will google consider this bad and penalize my new site from their search engine?