I don't think is possible on KDE 3.5.10, I haven't use KDE 3.x like in 3 years, there may be some workarounds, but I highly doubt it, since kdesktop just reflects your "~/Desktop" content, maybe by modifying the source code itself, and make a little kdesktop2 fork (you may only need to change the path it reflects), then again, I have never seen KDesktop code in my life, but it may be possible. However, it's certainly possible on KDE 4.2 :-P
Plasma is amazing, from notification to applets. If you don't like any of those, feel free to ignore them (you can disable plasma notifications and use Folder View as your desktop, tadan! you got your old desktop back).
Actually, I don't think you can. Also I'm not sure if it's a good idea.
I'm using OpenSUSE 11.1 BS, there's an option to use KDE build against Qt 4.5, I did try it before for KDE 4.2, but there was no point on using it back then, but KDE 4.3 is going to use Qt 4.5, so, should I start using the Qt 4.5 repo, or should I keep using Qt 4.4 for a little more? Thanks in advance for your help :-)