1. It is OK to have more than one loose end dangling at one time.
In fact, I'd encourage it. Loose ends dealing with the main plot of the story, loose ends dealing with the characters (undefined tension between them, unrecognized relationships, etc), loose ends pertaining to a side character that appears and disappears at random... there are so many options for loose ends.

2. Allow the readers to learn the answers to the loose ends as the characters do.
This is not always the way to go. Some authors choose to allow the readers to know the answers to the loose ends the entire time, and the reader gets to watch the characters work out the loose ends themselves. But this must be done carefully as to not lose the interest of the readers.

Allowing the readers to discover themselves is a more common way to keep the interest of the reader, because they want to know, too.

3. When it is all said and done, don't forget to close them, though.
It is a necessity to close them all up, eventually. Some may be closed as the story is progressing, and others might close up in the very last sentence. But don't be in a hurry! Close them up as it makes sense to close them in the progression of the story.