Am running 64-bit Centos Linux.
Have unpacked and run installation script, but find it stalls continuously at the Pre-Installation check.
The two warning which are apparently really errors (since installation is not allowed to proceed) are:

Session Writeable

---

> session.save_path: /temp

PHP LDAP Library

---

> Warning Icon

Could find no online docs to provide any insight into further troubleshooting.
Have provided annotated screen shots to confirm directory permissions are set per installation docs.
Any suggestions welcome.

Hi, CitrusSurvey,
I am not very versed in this matter, but a few hints.
The second - the LDAP - is just a warning.
Probably the LDAP extension is not activated in the php.ini (screenshot 1)

The first - the session save path - is the malefactor.
Did you check your phpinfo and the php.ini? (screenshots)
Then there is a hint in the manual:

Stuck at checking file system permissions

If SELinux is activated (primarily on CentOS) then you might get an error that the file system permissions are not correct but the list of directories is empty. SELinux prevents writing even though the permissions are on e.g. 777 or 755. You need to configure SELinux for your server correctly - check out the SELinux documentation.

Link to CentOS Docu

Best regards
Joffm

Updated PHP to version 5.6.28 in PLESK and the 2nd LDAP error went completely away.
One down.
However, the LimeSurvey pre-installation error/warning remains. Namely....

session.save_path: /var/lib/php/session

My permissions still appear good and the PHP.ini file shows:

session.save_path = "/var/lib/php/session"

I'll revisit the SELinux stuff you recommended, but this remains VERY odd and confusing.