When in doubt read up a bit. There is a ton of information available on this forum and in the Wiki.
The time it takes to load is a function of the command tree and its complexity and the number of plugins activated. And of course the speed of your computer. If you have just installed the app (correctly) and have not generated large payload XML files then it should load quickly.
The app not loading is not normally an issue, but I don't have enough information to know why you experience that, or think you are experiencing it. By default only one instance of the app can be open at a time. If another instance is running in the background that could prevent a new one from opening.
You should not be editing the XML file yourself especially when you do not know what you are doing. You have probably created an invalid XML file which would explain some of the issues. Click edit on the main menu to modify your commands.