There are some big differences between Judo and wrestling. The main difference is that in wrestling you're trying to pin your opponent and in Judo you're trying to submit your opponent. Also, wrestling does not have the throws that Judo has and you're much more restricted as to what you can do. In wrestling you can't choke your opponent or use any of the joint locks that they use in Judo. A wrestler would have no problem pinning a Judokan but a Judokan wouldn't care if they're pinned since they can still fight. Likewise a Judokan would have no problem getting a wrestler in a submission hold and once somebody is in a submission hold the fight is over. If you're looking for self defense I would say definitely go with Judo. Wrestling is not meant to be for self defense, its meant to be a sport and its not intended to be used for self defense any more than other sports such as Tennis or Golf.
Judo matches can be won by throw, pin, or submission. Due to the way the rules are currently structured, throws are most common.
Most throws found in Judo can also be found in wrestling, although there are some variations you won't find because they rely on gripping the gi. There are also a number of takedown variations used in wrestling which you won't typically find in Judo. Overall, the study of throws and takedowns is probably equally deep and wide in Judo and wrestling.
Even though most modern sport wrestling rules don't allow chokes or joint locks, wrestling can be and has been used very effectively in self-defense. As drop bear notes, this has been true for a very long time. You can read old fencing manuals which emphasize the importance of wrestling skills, you can watch real fights on YouTube in which wrestlers absolutely destroy their opponents, or you can look at the many old UFC matches won by wrestlers (before the sport evolved so every fighter was proficient in wrestling, jiu-jitsu, and striking).
BTW, it's judoka, not judokan.
Has there been a Judo match won by a sub?
I dont think that is too common.
Plenty of Judo matches are won by submission. It's not as common as wins by throw, because the rules limit time allowed on the ground. The flip side of this is that those judoka who do specialize in submissions get really good at hitting them
fast when the fight hits the ground, because they only have a short time before the ref stands them back up.