Could/would Rand Paul really singlehandedly bring on a depression?

Unless you follow standard rounding procedures. I fail to see that as terribly unreasonable.

Why even have a debt ceiling if you just keep raising it every time you get near it? Might as well do away with it.

The debt ceiling is a limitation on the Treasury, not on Congress. It allows the Treasury to issue and sell debt as it sees fit to allow for the day-to-day funding of government.

99 Senators present and a simple majority is needed. 50 Senators vote for the bill. Did it pass?
Accorording to the authors line of thinking, no!
The authors would determine a majority as 1/2 of the members + 1. Half of the members is 49.5 and so 50.5 Senators would have to vote for the motion so it fails for half a vote.

Now turn that around. 50 Senators vote against the bill. Did it pass?
Accorording to the authors line of thinking, yes!
Because by the authors determination a majority is (again) 50.5 Senators. Since fewer than the majority voted against the bill, it must have passed.

Hmm. Perhaps not singlehandedly, but he may have widespread support after all.

He looked like an unprepared idiot on Sunday morning TV. He was very unimpressive. Spoke in political speak and showed nothing.

Prepare yourself to hear every Repub and all the Fox personalities to say "its not about revenue, it is about spending’. It is about to drive you nuts. Paul, Cantor and all the Repubs came up with the disinformative slogan all morning.

No. Once he has the floor, he can hold it until he yields. As as long as he stands and keeps talking nobody less can get the floor to call for any motion, including a motion telling Paul to shut up.

He obviously can’t keep this up forever.

Indeed. They’ve already started on why tax cuts should get a free pass when we’re talking about balancing the budget. Not “raising taxes in a recession could be bad for the economy.” They mean not at all. Deficits due to spending are going to crush our children…but any deficits due to tax cuts don’t count.