[ntaw]

1) Can a Lord start a game without being attached to a squad?

Yes, but it leaves him vulnerable.

2) If a Lord is attached to a squad at the beginning of a game, can they detach themselves mid-game so they can re-attach to another?

Yes, he simply need move out of coherency with the squad he's attached to and into coherency with the new squad in the Movement Phase.

3) If a Lord can start a game without being attached to a squad, can they attach to one mid game?

Yes, he just has to move into coherency with the unit in the Movement Phase.

strat with Vargard Obyron being unattached and after deathmarks deepstrike and use their abilities, Vargard Obyron attaches to the squad (he would be within range) and teleports the squad allowing the deathmarks to use their deepstrike special rule a second time in the game

You can indeed attach Obryon to the squad to double up on their DS bonus, just not two turns in a row if you take the Deathmark's Interceptor-esque shooting option when they arrive.

 

[ntaw]

So once he removes from one squad he has to reattach to another squad within the same movement phase?

Everything in the BRB points to that being legal.

I want to make sure I understood this correctly.

Are you familiar with the Deathmark's Etherial Interception rule? Your list is better written as such:

- after an enemy unit arrives from DS (in the enemy phase, could be T1) or T2/3 on a 3+ Reserves roll (T4 automatically) Deathmarks DS in and shoot. Note that if they arrive and shoot in the enemy's Movement Phase they can't shoot in their subsequent turn.

- that turn, or on any subsequent turns, Obryon attaches to DM Group / Obryon detaches from current group and attaches to DM Group

- the turn following the Deathmark's arrival and Obryon's attachment to the unit, Obryon teleports out with DM Group

 

[ntaw]

Can that be done at any time in the enemy movement phase on T2/3 on a 3+ Reserves roll?

The moment any enemy unit arrives from reserves at any point in the game (T1-T4 I guess since there's no Reserves after T4), so long as you're in Reserve you can elect to show up at that moment (interrupting their actions) and fire at the end of the enemy Movement Phase. "This unit may choose to immediately arrive" means there is no need to roll.

 

[ntaw]

Ok. So Etherial Interception only functions if the enemy deepstrikes in unites or bring units in from reserve?

Deep Strike Reserve, sorry I missed that in my initial type up.

can it be used at any time against any enemy unit during the enemy movement phase?

One time use at any time of your choosing provided the Deathmarks are in Deep Strike Reserve and the enemy unit that just arrived came from Deep Strike Reserve. It's all about that "may choose to arrive".