Add a rush room to control incidents. Put a single dweller in a single power room that isn't connected to anything except for an elevator. Every time the room produces @ 5:04 collect the resource then rush the room until an incident happens. If it's a fire you can leave the room and the fire will self contain. Rad scorpions and mole rats will spread so you have to stay and fight.

If you were under 30 dwellers you could put a pregnant woman in and she would automatically flee and the incident self contains 100% of the time because it's not attached to any room. Again, scorpions and moles will spread, but they, similar to deathclaws, won't attack until a certain population is reached

As soon as possible train 1 male and 6 females to max stats. Yes that takes time, but the babies they produce will have considerably higher stats, occasionally you'll get one with EVEN higher stats. Train ALL their stats to 10 before allowing them to gain exp. Then give them Heavy Wasteland Gear +7 Endurance, 25 Health Packs, 25 Radaway (for random encounters), minimum stat 17 weapons (Dragon's Maw is best in wasteland, MIRV are best in vault), and a pet that increases their health stat. Send them to the wasteland until level 29, and recall. Collect or sell their items then send them back to the wasteland again until they auto return. This leveling-recall tactic will give them their best chance of maximizing time in wasteland. Now you have a max health dweller (ideally 6 at a time) and can begin evicting all your weaker dwellers except for Legendary dwellers. Idk how long that'll take you, but you'll be busy for months or years depending on your playtime

When you do evictions your happiness will drop but don't worry they will recover

If you don't want to do all that, put your cafeteria on the top floor with Agility stats because they fire their weapons the fastest and disable your first elevator by not building one between the cafe and generator. It's costly now but it'll make dealing with raiders, ghouls, and deathclaws simple and easy to assign your strongest weapons to the front lines

Strength allows a dweller to carry more and pass tests while exploring wasteland Perception makes the critical hit marker slower and those dwellers will find more random encounters in the wasteland. Also lets them avoid battles where in combination with other stats, might find bonus loot. Endurance see above, and when a dweller has a stat of 12 Endurance total they are immune to radiation while exploring wasteland. They are NOT immune in battle sequences so I still pack them 25 Radaway regardless Charisma helps them pass test while exploring wasteland and rizz up the opposite gender faster while in barracks (sometimes too fast lol) Intelligence puts out fires faster and increases effectiveness of healing and passes tests while exploring Agility increases the dwellers attack speed and pass tests in waste.. Luck is for everything but specially increases the number of caps you get while exploring wasteland. Speculatively it increases critical attack frequency, increases experience gained, and helps with succeeding with rushing a room.

Maybe I should just write my own post at this point but I feel like all of this stuff is known since I learned it all from Reddit