If the other guy has the weapons powerup and you don't have 4 pips to SYS, then yes you can die very quickly. Takes more than 3 shots, but it sometimes feels like less, especially with latency.
The game does try to match equally ranked players together, but it depends on how many people are playing. If there is only one match going then everyone will end up there. If there are several matches going (and they aren't full), then you should normally be placed in an easier one. However, being in a match with a 50 can be a good way to learn. Take the Sidewinder, put 4 pips to SYS and use the SCB. Most experienced players usually leave Sideys alone as they take too long to kill, so you can use the time to study their tactics while they maul everyone else.