Logic skill seems to help the learning of most other skills (not Athleticism or Charisma).

You can age anyone up, any time, by buying a birthday cake and clicking "Blow out candles".  You will get a list of every Sim currently in the house, including friends, neighbors and countrymen, and you can just select whichever person it is you want to age up.

You can set the Sims' overall lifespan (globally, for all Sims) in Options, or stop Sims ageing altogether, also in Options. I played this way for a while - I wanted the baby and toddler stage over quickly so that they didn't get tedious.

Sims can interact with ghosts as with normal sims. They might use the household appliances, even cooking themselves dinner. Fire alarms become even more essential!

Sims can live off the land, or in this case, the city. Try harvesting from fruit trees on community lots. Eat from picnic baskets with free meals in the town square. If they need money they can busk - play guitar - in Community Lots, or hunt for sellable rocks and gems. They can also nap on lounge chairs or park benches or ask to sleep over at a friend's. This is a kinder Benefit State than RL. 

However - sleeping on the ground only gives 1/2 an hour's sleep. Do 2 inappropriate things at a friend's house and get kicked out. Teens are still subject to curfew so will get nabbed by the police.

Sometimes romance just doesn't seem to be in the air, no matter the player's intentions. I have one couple who have lived together for Simyears, have three children, and never kiss except in bed, and still regard one another as "Best Friend". I've never had the propose Engagement come up on either of them. It seems relationship levels are scored separately for each Sim, and might be bugged. Workaround: use EnableTestingCheats True and manually lower their relationship bar, then push it right up to the top. Then Flirt! 

If a family breaks up, there is a relationship "Ex Wife" or "Ex Boyfriend", etc.

There are cars similar to Nightlife cars in Sims 2. However Sims mostly seem to use taxis.

There are ridable bicycles, but I have yet to see my adult Sims using them, though kids do.

Make a meal, store it on the food replicator, you get a certain number of charges which depends on the quality.

It's good for stocking up on group meals. Once meals are stored, replicate a meal. Upgraded it holds 3 different meals.