Remote desktop doesn't send remote screen to the local PC. Instead it sends commands to videocard (and then local videocard create a new image). Radmin sends actual screen. If you have 2048x1024 resolution at a remote PC and 1024x768 local one, you need scroll bars or distortion. It is like a having a big paiting. You cannot just fit it into small frame.
And Remote desktop instead sends commands to another artist "There should be a human and there a house..." to create a new paiting.
Ok, there is a map for you. We are working now on our next release which will contain most of these wishes. But we have a strict internal policy: we are not releasing raw products, thats why we cannot provide ETA, we just don't know exactly when testing and polishing end. Hovewer next release isn't in a very distant future, thats why we do not want to create small patches - most wishes and issues will be resolved at next release.
I know that my answer still has some mist, but I cannot provide more information and I cannot provide any timeframes.
Probably feature of limiting connections amount won't be implemented, there is why:
Imagine that for some reason remote user login then connections aborts, but without immediate TCP/IP timeout. Or remote user just forget about his connection, then nobody will be able to connect to this Radmin server until issue resolves. Hovewer it is still the subject of discussion in Famatech.
Actually, Radmin could conflict with another remote control software, especially if this software uses mirror driver technology aswell. But nothing "bad" could happens, at maximum sone or both remote controls will fail until you remove a second one.