I want a very simple template.

All I need is a page where I have a bit of info about my business with my address and e-mail and a few links to pages of products. On those pages I want product picture thumbnails that can be clicked for larger images, with descriptions which will be very short.

Also on those pages should be boxes to enter the number to add to the cart and buttons to add to cart, with of course a checkout button.

I want to take credit card payments with PayPal.

That is 100% of what I need. I do not need or want product reviews, who's online, languages, currencies (I only take US$), search or 99% of the other stuff I see on the default main page of Zen Cart.

I especially do not want to have it where people have to create an account and login just to buy stuff as most of my customers are not repeat customers. They only need one or more of the items one time and that's all.

I make reproduction parts for old cars. I used to sell on that big auction site which has become far too greedy so I want to sell direct with a website to make buying very easy.

http://partsbyemc.com <-simple! With some links added for Hudson and Nash and Other, still simple. That's what I want.

I have Zen Cart here
http://partsbyemc.com/catalog <-complicated! My mostly senior citizen customers would run away in confusion from that.

It's hosted on Site5.

One other thing I want is an item where I can enter anything for item name and price then credit card info. That'll be for all the car parts I have and for use with an Android phone for mobile sales of parts at car shows.

In your admin > tools > layout box controller you can turn off those you do not want

There are lots of free templates viewable at (sorry, site offline). Some are already clean and simple, and you can turn off most all of the extraneous functions in admin.

Put your homepage content in Tools > Define Pages Editor.

For the guest checkout you want, try COWOA in Free Addons.

The generic blank product can be set up as a product with price $1.00, and the customer can enter the "quantity" they want to buy. You can even have a text input attribute for this product so they can add a comment about what they are paying for.