7 ideas for updates - please consider!

@purpleinmyblood you can do some of these things already in the game, yay!

So, you can indeed make outdoor kitchens and have outdoor music. I regularly do both of these things particularly in warm Sims worlds. Sometimes just a bbq set up but sometimes with a stove too. There are some kitchens that look just right for outdoors. The one from Island Living looks good but for me, the base game ones that have matching bars are perfect so you can have an outdoor kitchen and integrated bar with bar stools. Place your music player on the bar and you're ready for a party! I do that or add a wall mounted speaker. Sometimes I use a cover but sometimes I don't. I've attached a example of an outdoor kitchen and dining space in my vineyard.

I forget which skill books I've read too. So I delete the ones I finish. Otherwise I accidentally pick them up again.

You can capture bugs in Outdoor Retreat. I used to like capturing them in Sims 3 wherever you went. I used to do that to earn extra cash, but I miss the lizards 😞. You can pick flowers and break rocks in the base game. It's seasonal though if you have Seasons installed. Shell collecting is a fun hobby that was added with Island Living. You just point at the sand to start beachcombing and find shells and...other surprises!

You can build your own community lots and shops anywhere (shops with Get to Work). You can turn any lot into a park just by changing the lot type in the top left hand corner of the screen. Each lot type has required items you'll need to add but by clicking on the little warning notice that you need say, a chess table it will take you to the right build catalogue section.

City Living and Snowy Escape have the best festivals. Island Living has some too. You could create a specific lot of your own to add festivals too. It would just mean manually putting up and taking down decorations. You'd use the Social Event tab on the phone to invite attendees and bar staff, etc. With the other festivals created by the game the decor appears and disappears automatically and staff turn up to serve food and drink.

Some of these things require additional content but if it's content you already have and you have questions just ask!

Edit: I've attached a couple more outdoor kitchen setups with a clearer view, there's no cheats used for these ones. For PC players I've seen some amazing ones done with CC.

@purpleinmyblood Here's some fun community space examples. Whalebert's Water Park (Pool Lot Type) and Firefly Park (National Park Lot Type). Firefly Park has an outdoor movie theatre using the Little Campers kit outdoor screen but the Movie Hangout pack also has big outdoor screens too.

The third lot is a Sci Fi park that is also a National Park Lot Type. I've made a similar park using the base game.

As you can probably tell, I love designing community lots! Art spaces, food courts, shopping malls, rinks, bowling alleys and pubs. You name it I've probably had a go at making one. I put a lot in Newcrest, Willow Creek and Oasis Springs as I don't use those worlds as much.

For your first point, there are skill books you can purchase from the bookcase. I did the research so most books follow the same general pattern. The first book usually is from level 1 to 3 in skill the second book is level 4 to 6, and the third is level 7 to 9. to get to level 10 in skills, you need to use the skill. You do have to pay attention to the skill level the sim has on your own to know which book for them to read. The books for skills that only go to level 5 are a bit different, but after the first book, I generally use the skill to make it go higher faster.

As for your second point. Certain packs came with festivals/events preprogrammed. Those packs are City Living, Snowy Escape, and Cottage Living as of right now. For rent has a market but since I do not own that DLC, I can only predict it may be act the same. You can create your own events in base game by throwing a social event and mimic a festival if you desire, but there are going to be limitations.

There are electronics that are made for outdoors already in-game and there is a kitchen sets that look great outdoors, depending on the packs you own. There is at least one in base game. If you have seasons installed, there are things you need to do to protect the outdoor electronics from the rain/snow.

You can already pick flowers in base game and that will level up your gardening skill. You can already get collectables from rocks in base game. They have regular spawning spots around the 3 base game worlds. The worlds that come from other packs are hit and miss with those. Island Living is the pack you need for shell collecting. If you own Outdoor Retreat, that intrduced bug catching. The Seasons pack does have an effect on those spawning too.

Leveling up your cooking and gourmet cooking skills is how reciepes open up in Sims 4. It is a little different, but it is like you learning muliple recipes as you level up in those two skills. The more DLC packs you own also adds recipes. WIth City Living pack, you can eat foods from stalls to learn recipes.

With your last point, you can easily do this by knowing what you named the lots you placed. Base game has a few lot types, with others being exclusive to certain DLC packs.

From what I am reading, you want to actually play Sims 3. Please know not everything is going to 100% translate exactly the same as the previous iteration of the franchise, but you can have a similar experience depending on what other DLC is owned along with the base game. You can have an amazing experience by learning the now mechanics and quirks the SIms 4 offers.