This is just a documentation of my experience. Maybe one day someone interested might see what caused all this. I am not the only member here to experience some or all of these errors.
First there was the old:
Check that certain classes haven't been defined by PHP plugins Your version of PHP has defined some classes that conflict with SilverStripe's. The following classes are at fault: HTTPResponse
Fixed this by renaming all instances to something else like; SSHTTPResponse
Warning: fopen(/tmp/silverstripe-cache-home-thesite-public_html/manifestClassParse-_home_thesite_public_html_cms_code_AssetAdmin.php) [function.fopen]: failed to open stream: Permission denied in /home/thesite/public_html/sapphire/core/ManifestBuilder.php on line 398
Fix this by manually creating directory; "silverstripe-cache"
After all that I have:
[Warning] HttpRequest::__construct() expects at most 3 parameters, 5 given
Line 112 in /home/thesite/public_html/sapphire/core/control/Director.php
Still no joy with the SS installers :(