Fallout – Is it possible to duck under melee attacks by crouching

According to the wiki, there are 4:

• Brotherhood Ending

Supported by the rebuilt Liberty Prime, the Brotherhood assaults the Institute and blows up its reactor. For the player character's service, Elder Maxson promotes the Sole Survivor to the highest rank of Sentinel.

• Minutemen Ending

The Institute is infiltrated and destroyed, sparing the Commonwealth of their oppression.

• Railroad Ending

With the help of Deacon, Tinker Tom, and a stolen vertibird, the Sole Survivor infiltrate the Prydwen and destroy it from the inside, causing it to crash. Later, the Institute is infiltrated and destroyed. The two organizations most opposed to Synth freedom are eliminated and the Railroad can continue its work in relative peace.

• Institute Ending

The Institute and the Sole Survivor attack and eliminate the Railroad. Later on, with the help of Institute synths, Liberty Prime is hacked and shoots the Prydwen out of the sky. After returning to the Institute, the Sole Survivor has a heart-to-heart with Father and assume his position after he dies.

Apart from having enough food and water, a strong defense (higher than food + water total to minimize attacks) and a general absence of attacks on your community, the happiness is mainly controlled by decorations and luxury.

Adding televisions, rugs and non-essential furniture (anything other than beds) to your settlement will increase the happiness of people living there. Basically, if you try to furnish their homes with care, they appreciate it. Who would have thought?

In one of those endless "How to foster your settlements" guides I read that apparently, the most efficient way to raise happiness in terms of resource/performance is packing any and every vertical surface with paintings. They require only wood to build which should be in overabundance and don't take up space on the ground for essential things.