For your questions 1 and 1a, youre correct. Mercbeasts setup uses one button to send key presses in game, as a alternative to no in-game macro system. You can set each action to delay x amount of time. Soooo, "it depends". Whatever skills or attacks in game you want to use as a combo key, and this is obviously dependent on what class you play, and how you want to play it. This is your spamable key. And yes, the companion attack is a toggle. its not a spamable key. You press it and they go.
Now, personally, this is not how I currently have my game set up. I altered from Mercbeasts framework and developed my own from Mosg's "Holy Grail", and Remanz Clickbar healing. I like to press each button for each skill or attack. (to be fair), I do have some combo keymaps set up.
I created a DPS1 through DPS6 and these are my regular "go to" skills. Then I just setup the in game skills with the particular slot and press what i need.
Briefly, mine looks like this...
Keymaps
+ Apps Control (set)
- Target Me
- Heal Me
- Heal Other
- Assist Me
- Follow Me
- Companion Attack
- CC Ability 1
- CC Ability 2
- OShit
+ Apps Warrior (set)
- DPS1
- DPS2
- DPS3
- DPS4
- DPS5
- DPS6
- DPS7
- Follow Jump (no action)
+ Apps Sorcerer (set)
- DPS1
- DPS2
- DPS3
- DPS4
- DPS5
- DPS6
- DPS7
- Follow Jump (no action)