PuTTY for Symbian OS can only use private key files created with PuTTYGen in Windows. See the user's guide for more information. You may also be able to use PuTTYGen to convert OpenSSH keys to the PuTTY format.
Some S60 third edition phones, including Nokia E-series ones, disable self-signed application installation by default. You need to change software installation settings, see the README.txt file, the user's guide or this installation note.
Yes! There are two UIQ 1 and 2 ports available, one from Robert Horvath and another from MobilEyes AB.