- Do you think OKW + Wehrmacht is "strong enough" atm?
Would going double OKW be better in the current meta?
OKW + Ostheer is a decent combination at the moment being able to beat any Allied strategy at any skill level. Double OKW is easier to execute and less punishing therefore less rewarding.
- Are the commanders and the build orders fine? Ofc you need to adapt in games, so please consider this as more of blueprint. Would you recommend any other commanders for 2v2?
OKW's commander loadout and build order looks fine to me except Luftwaffe: Swap it with Fortifications doctrine. You as Ostheer should consider adding a commander that grants access to scopes like Jaeger armour. Two commanders with Tiger and one strong air strike are enough. Do not build more than one PIV! You should rather save for Panther and Panzerwerfer than investing into more PIVs. I recommend your first tank to be a PIV as front stabilizing allrounder and your second tank to be a StuG if you need AT capabilities as soon as possible. If you feel comfortable enough with PaKs and PIV as your main source of AT you should advance to Tier IV and purchase what fits your current needs most (AT + damage tolerance? Panther! Indirect fire vs team weapons? Panzerwerfer! Want to troll? Brummbar!).
- Do we miss out on any obviously strong units/combinations that would help us?
Jaeger Armour (Scopes, Reconnaissance and Elephant: at least the first two of them are useful in every situation) in combination with Spec Ops (flares for more vision for your Elephant and Command Panther of course). If you combine mark target of Command Panther and all your team's vision granting abilities you will see how the Elephant turns every Allied vehicle into burning wrecks in no time.
- What can we do against the stalling/turtling? Base rushes? More harass on their cutoff? Build more/faster fuel caches to win the tank game?
I don't warrant that my plan will work in 100% of situations but if they turtle one side of the map your team should fortify the other side to a) guarantee you reach late game and b) to ensure that your team at least holds its "natural" ressource points and one VP. If you encounter emplacements (mortar pits, bofors etc) you can try out double Snipers with Infrared Halftrack/Scopes to spot counter Snipers. Due to using two Snipers as your primary attacking force you will barely take casualties (provided you keep your Snipers alive) which will give you enough Man Power to construct caches. Since your opponent has invested most of his MP in static units he won't be able to overrun your Snipers - not even speaking of OKW support. Keep your Snipers draining hostile Man Power (which might trigger your opponent to execute dangerous, crude pushes that you can use for your advantage) and rush out one PIV while your mate can go for Stuka -> T4 Flak Halftrack -> whatever tank you need. You should save for Elephant in the long run to dominate hostile armour. Your OKW mate can alternatively go for Howitzer and the 300 muni barrage of Fortifications Doctrine.
- StuGs or P4s or Panthers? What is the ideal combination?
See above. General rule: Never more than one PIV!
- How to play vs early Mortar Pits or Soviets with the 120mm mortar? Rush them with Luchs/222 or try to counter-bombard them with ISGs?
See above. Walking Stuka works best against 120mm mortars. An very aggressive but risky approach would be to build two mortars then two Grenadiers as soon as you see UKF on the loading screen. While you hold a central point of the map with a garrisoned MG42 (the garrison was successfully rushed by Sturmpioneers in the best of worlds) that covers your two mortar teams your mate spots possible emplacement constructions with Kubel's vision. Your mortars will help your OKW mate to dominate engagements against Tommies and other Allied infantry and two of your Grenadiers will support him of course. Build a flame HT as soon as possible to push your advantage and be sure it is covered by AT.