First of all, don't place your schwere panzer hq so near to your medic truck. One incendiary strike and both get damaged. Secondly the schwere panzer hq should've been infront if your medic hq, somewhere near your fuel point e.g.
By your placing you created a blocked road for your own tanks and a huge arty magnet. Check this guide for further information :
http://www.coh2.org/guides/34730/tip-of-the-week-9--okw-truck-placement#1564
Secondly try organise your units better; there is no reason to cap with 3 squads worth 1000mp one point. Split, cap 3 points at the same moment or use one squad to cap and the other to flank or fight.
So situations like this are omitted:
So to your points:
Yes you could've won the game as soon the P4 arrived. Your opponent had no AT and was building 2 at guns in panic, you should've been more aggressive with your P4 in that moment.
Although your opponent had less infantry, you were not really using the fact that you had more infantry. You could've cut him off early, camp his fuel etc. But somehow you were happy with the territory you had and were leaving him enough breathing space for a comeback.
It's very important to plant mines on the side routes in minsk pocket, so tanks like the KV8 can't simply sneak up and destroy your buildings and infantry. You can't be everywhere, the map is too big for that, so it's important to cover "open" spots with mines.
Also i'm doing a horrible job a couple of times to cap a point that is only defended by one MG in a house. But my vg's get pinned when approaching the house before being able to throw a grenade. How should I have done this?
Use 2 squads, spread them out. Approach the building with one squad which draws the fire. Then use the second squad (volks) to bypass the arc of fire since the first squads draws the fire. Once you bypassed the arc of fire move to the house and throw a flame grenade.
Also you surrendered too early. You had nearly 1000 mp on the bank and still a panther. One sturmpio squad could've repaired your base, while with another falls you could've capped another vp to stabilize your bleed then you could've concentrated on middle + your vp while harassing the enemy vp. You can also use your panther to crush shocks/ push them around. He had not a single con squad the entire game, so you had not worry about AT nades at all. Tanks could've crushed as much as they wanted.