Nobody is quite answering your question about going into orbit. A simple hohmann transfer would be able to get into orbit without expending very much fuel at all at Pluto. This talk of it going too fast to slow down is specifically because they didn't do a hohmann transfer.
Pluto is really far away, and the way a hohmann transfer works, the craft ends up moving very slow relative to the destination when it gets there. I haven't done the math myself but read it would take somewhere around 35 years to do it. But the thing is, it could have been done without being very expensive. That is, unless the nuclear generator doesn't last long enough. And nobody wanted to wait 35 years so instead they got going really fast and got an additional boost from Jupiter.
So the real answer is, they're going too fast because they wanted to get there in "only" a decade.
Pluto is really far away, and the way a hohmann transfer works, the craft ends up moving very slow relative to the destination when it gets there. I haven't done the math myself but read it would take somewhere around 35 years to do it. But the thing is, it could have been done without being very expensive. That is, unless the nuclear generator doesn't last long enough. And nobody wanted to wait 35 years so instead they got going really fast and got an additional boost from Jupiter.
So the real answer is, they're going too fast because they wanted to get there in "only" a decade.
(edited down to 35 years)