please check is 1and1 have some php accelerator...
you can see this in firebug, tab net. open any request and look into headers response info. Usually i see there something like "varnish accelerator" of something like this.
also ... what hosting type do you have on 1and1?

i asked softaculous team about this.
waiting for answer.

How do you handle size too small errors

how do you get it? i mean reproduce steps

hello.
Try to login into google checkout as merchant and go to tab tools->integration console. There you'll see error log.
Post it here.

 i tried to place order and going to contact form from success page - any problems

hello.
i checked that page and see that link is correct.
i guess you have trouble with session.
what "payment" do you use?
Send me URL as PM. i need to look.

Can you say specifically what I should rename or comment out?

I will include my php.ini file is multiple post to follow.

you wrote
/hermes/bosoraweb018/b221/nf.server/public_html/store.com/php.ini
try to delete comments there

Im getting this security alert on the server.

20130210T224244: www.store.com/index.php
PHP Deprecated:  Comments starting with '#' are deprecated in /hermes/bosoraweb018/b221/nf.server/public_html/store.com/php.ini on line 1 in Unknown on line 0
<b>Security Alert!</b> The PHP CGI cannot be accessed directly.

<p>This PHP CGI binary was compiled with force-cgi-redirect enabled.  This
means that a page will only be served up if the REDIRECT_STATUS CGI variable is
set, e.g. via an Apache Action directive.</p>

You can rename file php.ini(to use default php.ini) or delete comment line. 
We'll fix it in 1.1.4.

Can you show your phpinfo(); output ?