OSX has a built in speech synthesizer which is quite good if you're looking for English pronunciation.
You can open up the terminal and enter the following command:
say "Hello! How are you?"
For dictionary I use the Dictionary application which is shipped with your OS as well. You can import multiple dictionary files into it. Here is a tutorial to do that.
The best part is that you can type ⌘ + ctrl + d to bring up the inline dictionary in cocoa applications. It's really handy.
I don't know all of Text-To-Speech programs out there, but I think the current state of this technology is still a little behind.
Only the "standard" sentences, i.e. the most common ones, will be spoken with a good intonation. But in general, more or less, programs will behave like robots when pronouncing words.
Regarding the features you asked, anyway, GhostReader does the job and is actually fairly good at pronouncing. Although I'm not sure about the last thing you asked. The program is commercial but has a trial period. You can download single language packages from the site and load them from the program itself.
I was going to suggest Toau as well, but it doesn't have those features you ask, it's pretty basic. The advantages of this app is that it's free, and the interface is simple. The disadvantage is that it uses the Mac OS X library for language packages. When you want to change a language, it will take you to System Preferences, and you'll choose the language there. This is why it's not my first suggestion, while on the other program, you downloaded specific packages.
Best Answer
Dragon Naturally Speaking v6 may be an option. Trial available here. Have used with school and it performed well in loud environments as well as those that are quiet. Doesn't need an internet connection after downloaded, so is a very good idea. Also, the macOS built in dictation software may be downloaded for free, but is not as reliable.
For more, see this thread, which says