"how often does it happen?"
About as often as random probability suggests. For the record PB 2 years ago there were about 635 million tickets sold. With QP's accounting for 70 to 80% of sales there may have been 450 to 500 million of them for that one single drawing. That would mean about an 80% chance that at least one QP had the winning combination from the previous drawing, and about a 96% chance that at least one ticket had the winning combination from one of the two previous drawings. Even with more modest sales it's a certainty that once in a while a QP gets the winning combination from the previous drawing. On a related note, with millions and million of QP's being printed every once in a while somebody buying multiple lines will get two identical lines.
"Would you play the jackpot combination of last draw?"
No, but it's not because that combination has already won in the past. Most people would avoid it based on that, but with millions of people playing there are probably a few who think lightning will strike twice. I'd avoid recent winning combinations because of the possibility that it increases the chances of sharing the jackpot if those numbers happened to come up.
"Chances are big you wont win the next draw."
You can buy 100 or 1000 combinations and your chances if losing will still be big, regardless of which combinations you play.
"What kind of patterns?"
Perhaps that's a reference to the repeated numbers that I already mentioned. Many people have said that if they buy multiple QP lines some numbers may repeat on multiple lines more often than probability suggests. For example, if you play five lines for PB there will be 25 regular numbers and 5 power ball numbers, but the tickets may only have 15 unique regular numbers and some lines may have the same power ball number as other lines. That may mean that the RNG isn't s random as possible and it may be fair to call it a pattern, but a lot of players call it wheeling and do it on purpose.