Scenario 1: Party of adventurers vs an orc patrol

A part of adventurers enter an abandoned ruin. 

The party consists of: 

- Ambrose, a fighter with a longsword (WSF 5, length 3.5') and chainmail armor+shield (AC4)

- Alice, a fighter with a spear (WSF 6, length 6') and leather armor (AC 8)

- Alex, a cleric with a mace (WSF 7, length 2.5') and ring armor + shield (AC6)

- Amber, a thief with a short bow (ROF 2) padded armor (AC8)

Ambrose and Alice form the first rank, behind them are Alex and Amber.

In the middle of a corridor they encounter a patrol of 5 orcs at a distance of 30'. The orcs are carrying spears (WSF 6, length 5.5') and have AC 6.

Assume no surprise. Declarations for the impending round are completed before any initiative dice are rolled.

Scenario 1a. 

The DM determines that the orcs will charge into melee. The players all opt to charge into melee.

Order of Resolution:

Since all participants are charging, initiative is given to the participants by weapon length. There is no need to roll for initiative.

Alice, spear (length 6')

Orcs, (both ranks) spears (length 5.5')

Ambrose, longsword (length 3.5')

In this case, attacking from the second rank is explicitly explained in the rules. RAW, in a charge, only weapon length matters. (This is true even if one side is set to receive a charge.)

Who attacks who? In a charge, attackers may select their targets. Contrast with melee, where participants determine their target randomly.

Scenario 1b. 

The DM determines that the orcs will charge into melee. The players close to melee range.

Again, since a charge was involved, initiative is not required.

Order of resolution:

In a charge, the first attack goes in order of weapon length.

Alice, spear (length 6')

Orcs, (both ranks) spears (length 5.5')

Ambrose, longsword (length 3.5')

Why would you choose close to melee as an option? A couple of reasons, perhaps. Let's consider them.

One the players didn't realize the orcs would or could charge. At 9" of movement per round, doubled for charging (180'/round, or 18' per segment), they can reach the PCs in the first round and make an attack (you have to end your charge within 10' of the target). 

Secondly, while charging the attacker gets a +2 to their attack roll, they also suffer an AC penalty of +1 (ex, AC4 becomes AC5). Choosing to close to melee range eliminates the AC penalty, and also avoids possible double damage from weapons set against a charge.

Scenario 1c. 

The DM determines that the orcs will close to melee range. The players close to melee range as well.

No one makes an attack roll as both sides approach and enter engagement distance. No initiative roll is required.

Scenario 1d. 

The DM determines that the orcs will charge. The players in the front rank close to melee range. Alex, the thief chooses to fire her bow (discharge missiles).

Here we have a case with a timed action (the charge, which will take 2 segments to complete), and an untimed action, missile discharge. Which action resolved first?

We roll initiative!

The party rolls a 3, while the orcs roll a 1. The party won with a 3, so the order of resolution is:

Amber's 2 short bow attacks

Orc spear attacks from the charge

Any PCs within melee range of the orcs at the end of the charge 

Amber's attack goes first, as she has an untimed action not involved (ie, not a target) in the charge. Then we resolve the charge which grants first strike to those with longer weapons, followed by the now (in melee) any PCs within 10' (assuming they are not doing anything else).

 

Scenario 1e.

As 1d, the DM determines that the orcs will charge. The players in the front rank close to melee range. Alex, the thief chooses to fire her bow (discharge missiles).

This time the orcs roll a 6, while the party rolls a 4. 

In this case, the untimed action lost, so the untimed comes on the segment indicated on higher initiative die roll.

So the order of resolution is:

Orc spear attacks (segment 2)

Amber's 2 short bow attacks (segment 6)

Any PCs within melee range (10') attacks (segment 6)

It's worth pointing out that while the untimed actions occur in the same segment, the order of resolution remains fixed according to the chart on page 61, 

4. Determine the results of whatever actions are decided upon by the party

with initiative:

The steps are laid out from A-H. Missile discharge ("D. Discharge missiles or magical device attacks or cast spells or turn undead.") is listed before melee combat ("G. Strike blows with weapons, to kill or subdue.").

You should see that the initiative die roll can be critical in circumstances where you need to know if an action will complete before another one.