No you NEED to use volks, but don't fight engagements you can't win. Volks lose to penals in most engagements unless they outnumber the penals. So if you have 1 penal vs 1 volk, you should probably abandon the engagement unless you have superior cover.
Common build order from OKW is:
Volk -> Kubel -> Volk -> Volk -> Tech/Volk OR
Kubel -> Volk x3/x4 -> Tech
Sometimes the map doesn't allow for good kubel usage and you skip the kubel.
Raketens are also worked in there sometimes when an M3 shows up.
OKW metagame is very aggressive. Starting sturmpioneer is the key to your success. You need to make use of the unit more than just capping and need to fight with it. Key garrisons, heavy cover, cutoffs, choke points, deep points you can hide behind sight blockers. You need to get your sturms deep into your opponets "half" of the map and make him afraid to push points without an overwhelming force. Use your volks to backup your sturms, and then let the kubel cap your territory.
If you see he goes T1 as soviets you can expect an M3 probably. You don't have to go raketen but if you have the resources and at least 3 volks fielded you CAN. 4 volks is common currently, and you can plant mines with pioneers on hotspots. If you feel the M3 is coming you can have the kubel take territory near your sturms and volks to try and kill the M3 before it kills your kubel. A lot of players tend to just back the kubel away when they see the M3 but understand that the kubel can deal some decent damage vs the M3. The M3 will always win a 1v1 vs the kubel, but if you focus fire it with volks and sturms a lot of times you can trade out or even destroy the M3 before it gets the kubel.
Mech truck is currently favored with OKW into luchs sometimes coupled with a puma. The luchs allows you to keep your aggressive playstyle and try and keep your opponet off as much territory as possible. The puma is more just to push back the inevitable T70 that shows up in 98% of high level soviet games. If your Soviet opponet knows what the T70 can do, he will get one. If you don't go puma I would highly recommend 2x raketens. 1 is risking a lot, 2 is much more safe against a t70. If he has guards you need to try and beat them with overwhelming numbers and superior flanks. Guards are great at what they do and they're anti everything. You're not going to win 1v1 engagements vs a lone volks squad. Obers, multiple volks, a luchs can push them around a bit. Just be careful with vehicles as their DP28s can snag vehicles if they get to close inhibiting their movement. You can remove the snare by pushing the guard squad or moving out of range. If they catch you at mid range with button you're introuble. Their "Hit the Dirt" vet ability also gives them bonus Rate of Fire, so watch for that.
If you make it to lategame the OKW p4 is your bread and butter. A fantastic medium generalist but understanding what it can and cannot do will help a lot. If your opponet is getting T34/76s, the P4 will do great. T34/85s I highly recommend a panther. The 34/85s will out trade your P4 most of the time. The have better penetration as well as higher HP than you. This is why the panther does well vs them. For what the panther lacks in anti-infantry it makes up for in its ability to brawl with other tanks. It has high penetration, armor and a very sizeable HP pool that can run over your opponets armor if they overextend. Just becareful not to overextend with your panther. Su85s will have no problem taking shots out of the panthers range and penetrating.
A word of advice for OKW, do not ever go KT. It currently sits more as a noob trap for players who like "big heavy tanks". You'll get far more DPS and mobility out of 2x p4s, or a P4 and a panther.
Also understand your opponet as well. Understand that t70 that shows up in 98% of games shows up because it has good AI and decent AT vs some units, but with vet2 and vet 3 has outrageous sight range. We're talking cross map sight range with recon mode enabled. Consider yourself doing very well in the game if you can snag that kill, just don't lose your army for it, especially your raketens. 6 man soviet raketens are very frightening.
Thanks for taking the time to write that out. I really do appreciate it. I've been playing this game more or less since it was released but have been away for a couple of years due to getting kids and having bad internet etc. This really helped refresh my memory.
I have maybe gotten a KT a handful of times at most. I hate the big bulky tanks with a passion.
I've been going T1 to get fast fausts but perhaps i should wait a few extra minutes to bring me the luchs to help me wrestle map control back. The puma used to be my favorite unit. It hits really hard for it's size and most opponents underestimate it. I even used to go double pumas and duke it out with medium tanks with some success. However, i do feel my micro has gotten worse and it's very micro intensive, i will try to regain control of that sweet machine.
Again, thanks for your advice.