What benefit does upgrading walls have?

The basic concepts of walls are to protect your Town Hall and/or resources. At your current Town Hall level, upgrading walls may seem expensive, but the higher your Town Hall level, the higher level collectors, barracks, laboratory, and camps you can build. These allow you to attack stronger opponents to steal their resources, by winning battles and increasing your trophies (which makes you face stronger opponents).

Stronger walls and a well planned defensive strategy will prove effective (to some degree, see the bottom of this answer) in slowing down your attackers. While your attacker's troops are trying to get through your walls, your defenses (clan castle, archer tower(s), mortar(s), cannon(s), etc) will be trying to kill them. I would recommend putting your defenses behind your walls.

To answer your question though: Yes, but it depends on the wall breaker's level.
See below:

You can get a lot of information from (and source of the screenshot above) from Clan of Clan's Wiki Page on walls

Also, I mentioned "to some degree" because at higher levels there are troops that can jump over walls(hog riders), fly over walls, and there is a spell that allows all troops to jump over walls!

Yes it is. Another replier has shown you the chart for the number of wall breakers needed to break a wall. Each wall breaker takes up 2 spaces. Assuming a level 1 wall breaker is trying to break into a zap wall, it'll take up 30 spaces of an attacker's army camp (although I hardly doubt a person with level 1 wall breakers will want to break into an attacker's zap walls).

Not only is it important in terms of wall breakers and army camp spaces, there are also a few things to note about better walls: - it intimidates your attackers so you get attacked less (this can be counterproductive though if you only get attacked by really good players who can 3 star you) - better clans (which I assume you'll want to enter into one day because no one wants to stay in a clan that donates level 2 giants) usually have wall requirements. eg. min skull walls.

I can understand your frustration in building walls though. I absolutely hate them now that I'm doing my skulls, but they give a certain satisfaction when you're done, right? I have seen someone in global though with almost full purple walls but level 2 defences (no joking), so don't neglect your defences in favour of walls. But try to do the walls earlier, so you won't be scrambling with idle builders towards the end of your TH level to build them up especially if you want to max everything before the next level. Do them at your TH level too because the higher your TH level, the bigger the penalty and the more difficult it is to gain resources to do your walls or anything else for that matter.