DoctorDisco: Your post is far easier to follow, though! I wanted to put the numbers there if anyone was curious about it or wanted the nerdy details about it.

Griff: Yes, that's a good way to simplify it. The simplest way to explain it is this: EVs gradually become worth more as a Pokemon levels up, until level 100 when they're worth EV value/4. At lower levels, more than 4 points are necessary for one stat gain. At level 41, roughly 10 EV points are required or one stat gain, so those 33 EVs are worth a bit more than 3 stat points. However, at level 100, those 33 EVs will be worth 8.25 stat points, as the answer shows.

hyper beam: Yes, your understanding is correct. You can use this formula if you want to quickly work out how many stat points your Pokemon's EVs are worth: stat points = ((Pokemon's EVs/4) x Pokemon's level)/100. This is essentially what the formula does, except with natures, IVs and base stats also considered. I think you're right about stat changes being instant as well; I recall having stats go up as a direct result of Super Training, without leveling up the Pokemon. However, since you can't change base stat and IV values like you can with EVs, you'll have to level up the Pokemon for those to take effect.