i mean they have switched the way how factions are strong in diffirent phases of game, but aren't ostheer by design meant to be bit slow and rely on support weapons and then go aggressive later on?
Ostheer is stronger early on when MG42 doesn't die to frontal blobs. Average for the rest of the game.
Can't really review the replay but I can answer the first two questions:
1) Try to wire off cover or just destroy it with AT guns or other explosive weapons (just use attack move order and target the sandbags).
2) Grenadiers have higher DPS than Tommies starting at range 11 and down (which is close range). Your best bet is to ambush them at close range or outnumber them at long range. And remember, grenadiers on their own are worthless, you need to support them with your MG42 or at least pioneers with flamers.
In my opinion axis is favoured by players because because they lost the war. kind of trying to see history from the loser's side.
This fits more as an answer to why people want german campaigns. Personally, I prefer axis because they look aesthetically more pleasing to me than Soviets or brits do. British voice acting is the only reason I play brits though.