I can confirm that the Ottomas pregnancy glitch was patched not long after Seasons had been released.
And yes, you can create subfolders in the Downloads and SavedSims folder. It helps organize things, like different binned hair colors of the same hairstyle. All CC is in the form of .package files (no rar or zip files). There are also Sims2Pack files, but you just need to open them and they'll automatically extract their contents.
As for mods, there is the equivalent of the MCCC that I'm not allowed to mention because they raise the game's rating. It did let me fix the Ottomas pregnancy before it was patched. I also have a mod that prevents the butler from cooking food, because they do it whenever someone is hungry even if you still have leftovers, and there's no way to stop them or decide what they cook. I also have a small spelling fix for Mansion and Garden. It's not really big: it just changes "cunsumption" to "consumption", which bothered me and Maxis never bothered to fix it.
