[kde-linux] kde3 applications working together with kde4 versions

[SeaJey]

Good day to kde community.

KDE3.5 still my main DE, but I am frequently switching to KDE4.1beta2 or 
kde-nightly to see how the things will work in nearest future.
And I have some questions about team-work of kde3 and kde4 applications:

How can I set kwallet-kde4, konqueror-kde4, kopete-kde4 to be main wallet, 
browser and IM applications by default still to be able to launch there kde3 
versions?
I want to open link from akregator in external browser (wheel-clicking on 
it) - and konqueror-kde4, running on the same virtual desktop will open this 
link in another tab.
I want kopete-kde4 to autostart after logout - currently old kopete is 
launching instead of it.

And I want for example kontact-kde3 and kopete-kde4 to use the same wallet.

I think some softlinking will help me but I don't know how to do it properly.

Need your advise.

PS
Sorry for my english.