1/ The SIZE of the fed deficit is never a problem. Its INEQUALITY is always a problem. If more were spent on good things (helping people as long as not inflationary) & less on bad (bailing out the rich), the size wouldn't be a concern, no matter how large. 
2/ The SIZE of nat debt is never a problem. Its INEQUALITY is always a problem. The problem is the rich have too much wealth & the rest of us not nearly enough. If it were more equitably distributed then its size wouldn't be a concern, no matter how large.
3/ Federal taxes are very important, but they don't and can't pay for federal spending (and, in fact, never have).
4/4 To learn more in general, here's a good place to start:
