Again, I'm using MuseScore 2 so it might be slightly different for you, but if you click on the fermata a bunch of options should appear in the "Inspector" window (on the right side of my screen, but if you don't see it you can activate it in the "view" menu on top). In the inspector there should be a option for "time stretch", which determines how much the note is extended during playback. I believe the default is set to "1.0" which means the note is not elongated at all, but you can change this if you want. 1.5 would make it one and a half times longer and so on. Since someone else made your score, they'll probably have changed the option somehow, so if you want the note to be of standard length, set it to "1.0".
As for the gray symbol, things in MuseScore turn gray when they are marked as invisible; this means that if you export the score to a PDF file, the symbol won't appear, the inspector window should also have a box marked "visible" which you can check/uncheck as you want. Alternatively, if you want a thing to actually appear gray on the final score, the inspector window also has a colour option where you can make things any colour you wish. This works for any symbol by the way, so you can make notes and other things invisible or different colours as well.