Just hoping to answer a few questions with this post. If others have questions, I can try to answer them, but be aware there may not be very many answers. Feel free to PM me as well, but there may be some delay on a reply
Has there been any mention of downsides to household switching in Sims 4? In the Sims 3, you lose your active wishes and there's a good chance your sim's career could be changed, or they could break up with their partner or ruin other relationships because of story progression. Inventory is also at risk, as I would not trust leaving something like a collection helper in an inactive sim's inventory.
Revisiting an older question by Cheezey. It looks like Story Progression has been pruned back, so any changes made will have to be done by the player. As for inventory, we won't know if it is bugged until release, but that is certainly something that is usually patched fairly early if it is.
I've not seen anything about time in Sims 4, in Sims 2 when you visited a community lot time froze back home, so say you got there at 9am and left at 5pm you'd arrive back home at 9am, really messed up the motives and sleep patterns of your sims so I hope it's not like that.
I have an entry put up Turoskel on the information, but basically it keeps accurate time. If you are another zone/lot at 9PM, and don't leave it until 11 PM, it will be 11 PM when you return home. This doesn't apply to lots you don't control, though.
I am also on the fence about purchasing this. If there are no toddlers and no woohoo, how will I play my beloved multi-generational games?
DarkMetalScorpion is right: You still have Woohoo, just not as a separate skill (The SimGurus confirmed Maxis/EA felt discretion was the better part of valor on whether to have it as a skill or not, especially where the ratings board is concerned). So, you will still be able to do a multi-generational game