Brand New Dark/Dark Tanker-Any Advice?

I havn't played a Dark/Dark ANYTHING yet-I have peeked at a couple of the guides here but thought I would ask for some general advice:
1: What's a good ancillary with this? The Fighting pool?
2: Would going with IOs ASAP be a good idea or should I wait till I'm in my 30s?
3: I usually alternate between my primary and my secondary when it comes to acquiring new abilities-should I get all my tanking abilities FIRST and then worry about attacks?
4: How useful is the stealth power if I'm a tank? Should I skip that one?

I consider Dark/Stone superior to Dark/Mace for stacking stuns. Fault ftw. However, not what I believe the OP is after.

1. Fighting is a good pool to take for DA. Tough helps significantly to improve your SL resistance, which is not overly fantastic otherwise. As for Weave, I'd take it only if you have a significant amount of defense in the build (which can be a very nice way to go). For the APP, it depends what you need at that point really. Conserve Power and/or Physical Perfection could help significantly if you have end issues. You may want to flesh out your area damage, and a targetted aoe may be better than a cone attack.

2. Certain IOs would be very useful early on. In particular, I'd look at getting at least one knockback IO. Dark Regen benefits greatly from some frankenslotting and the Theft of Essence +end. When to frankenslot or build for set bonuses is largely a matter of preference.

3. IMO, a tank should pick up at least a second attack early. Especially when solo or on small teams the extra damage can actually keep you alive better than another toggle in some situations. It also depends whether you grab Death Shroud straight away; it's ridiculously efficient damage against substantial groups (you can probably do quite well soloing with this power, setting for -1s with large virtual team size) but some people dislike the toggle management before stamina. I'd also aim for Siphon Life at 16.

4. It provides immobilize protection, which is a good idea if you don't get CJ. It's also a little defense, which like Weave is of varying use depending on your build.

1: What's a good ancillary with this? The Fighting pool?
First, the Fitness pool. You NEED Stamina. My dark/dark is only level 27 and already has six toggles. He'll be getting two more at levels 28 and 30. The Fighting pool is a good idea, in my opinion. Tough is one of those toggles I just mentioned. If you don't have a preference about travel power, I'd go with Leaping for two reasons:
1) You can get immobilize resistance early with Combat Jumping.
2) Combat Jumping is 2.5% defense - not much by itself but dark armor has some defense in it.

2: Would going with IOs ASAP be a good idea or should I wait till I'm in my 30s?
I feel that low level IO's are rather deficient in their effectiveness. I start slotting IO's around level 35. The exception is those where the power is independent of the level - for example, -knockback, which I slotted at like level 15. Also, the Miracle +recovery unique, which I slotted at 17 (the set starts at level 20).

3: I usually alternate between my primary and my secondary when it comes to acquiring new abilities-should I get all my tanking abilities FIRST and then worry about attacks?
Well, right off, one of your attacks is a really awesome power. Siphon Life is decent damage AND a self-heal. Sadly, you can't get it until level 16. Overall, you can afford to go a bit light on attacks initially since Siphon Life is dual purpose and, if you go with the Fighting pool, you'll have Boxing available. At level 27, my tank has four attacks, including Boxing.

4: How useful is the stealth power if I'm a tank? Should I skip that one?
You don't want it for the stealth. You want it for the 5% defense to all. It also gives +PER, but you mainly want it for the defense.

I agree with everything that's been said to this point. I'll just add a little more.

What type of tanking will you do with your DA/DM?

1. As far as epics go, Energy or Pyre. Energy if you're still having endurance issues, Pyre if you want more dmg, namely AoE with fireball. Fitness and Fighting as stated.

2. Get the Kinetic crash 4 socket bonus if you need the -KB early on and don't have the cash for the other IO's and don't mind using the slots. I will say though that once you do, respec out of this immediately as the slots will be needed elsewhere.

3. You can alternate as you like with the exception of some core abilities which should be chosen as soon as available. Stamina is one of them.

One more thing... Cloak of Fear and Touch of Fear. Either get both of them or don't get them at all. Cloak of Fear will require heavy slotting to make any use of it while ToF does not. The ones you want feared are the bosses. CoF can't stack with itself and you don't want to repeatedly use ToF, especially when the time comes to use SL/DR or DC.

Ok, make that two more things. You can't stack anything from your secondary with OG but it has a much lower endurance cost than CoF and doesn't suffer from the accuracy penalty.

Solid advice,gents-thank you.

Thanks for posting this topic, I was kinda stuck on my dark/dark brute but the tips here have given me something to think about.