Got it on the halftrack, tho will it be worth it late game? It cost quite a fuel. - also, I've changed my load-out after watching the first review, I've added a command panzer, and also thinking of removing Encirclement Doctrine but keeping the close air support. - Can you suggest a second commander?
The halftrack is basically always worth it. It gives so much field presence. The idea is to create a hard point around it that can't be pushed off. Keep all your grens and your mg around it and control key points of the map. Use your pioneer squad to harass other parts of the map. (Be careful not to lose it!)
As for another commander, I would suggest Mobile Defense. The puma comes at 5 CPs and can give you the mobile AT needed to deal with the M5/stuarts that are the meta right now. The command tank is just crazy as well. The buff it gives is nuts, use it to anchor your hard point. The Ostruppen call in squads are also excellent for harassing parts of the map that you can't afford to send a grenadier too. This will force your opponent to commit at least one(likely more valuable) squad to deal with it, and weaken his main force.
I've got a question, when is the right moment to upgrade a healing bunker? - I obviously need to work on MG Bunker management as you have said, is it still worth it if I keep being aggressive and building it defensively so that when I fall back, theres something to cover, or not to build it at all?
Regarding bunkers, I wouldn't build your medic bunker until after you have your first pak on the field. Getting your AT out as fast as possible is the most important thing you can do as Ostheer. A medic bunker won't do you much good against a 6 minute M5 or stuart. I also think it's less important than getting an early LMG on one of your grenadier squads, the earlier you can start the MP bleed on your opponent the better. A good time to invest in a medic bunker is after you've established yourself on the field against a potential light vehicle rush, and before you tech to T3(if you plan on teching T3).
As far as MG bunkers go, I wouldn't bother with them. Good players will deal with them easily, and that 60 munis would be much better spent on another LMG for your grens or a teller mine. If you are struggling with keeping field presence, the halftrack is the solution, not an MG bunker. (No I won't shut up about the halftrack
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EDIT:I'm not a fan of bunkers, but they can be useful, just don't make it a priority. You can work one into your build in the mid game if you're floating some MP or resources they can be useful to be a nuisance at a key point.
Is getting two panzer 4s good choice too? or teching up to t4 and then panther later on would be better?
This varies on the game, but generally speaking I think a 2nd P4 is going to serve you better in most situations. Paks are such an effective AT gun that investing the fuel in T4 and a panther just isn't worth it in most games. One of the only situations that a panther could be worth teching to is against an IS-2. However, if you're playing with an OKW partner, let him build the panther, since he won't have to tech for it.
I'm starting to use Sniper against USF but it gets extremely hard to micro and keep it alive late game, whats the ideal situation to call a sniper?
The sniper is a map dependent unit. Maps like minsk, Rails and Metal, Crossing in the Woods, and Moscow outskirts are ideal for snipers because they generally have open sight lines, and limitied areas of the map to get surprise by enemy infantry. You can choose a sniper on other maps, but as you said you have to baby sit them in these situations and it becomes a real challenge to micro.
Snipers are very effective against USF rifle play and T2 soviet play (and T1 soviet play if you are patient enough. Basically you just use your sniper to keep the soviet sniper from going HAM, and look for opportunities to counter snipe)