I would like to ask about the offline mode of gaming in StarCraft 2. It seems to lack some things can be accessed compared to gaming online. The things I discover for offline are such as; you cannot play with mods, brood war ost will not play, etc. I wish something can be done about this, because not always that players want to play online, and they still want access to mods/ prefer brood war ost to have fun 
Assuming you mean arcade maps, this is because you cant download them from the internet to play them on. Blizzard cant fix this.
I havent heard of this one, but did you check to make sure it was enabled and that you were playing a vs AI game (as opposed to campaign, which uses its own soundtrack)?
Yes it was enabled, but if you play offline there won’t be brood war ost. It may sound like a “meh” thing but it kinda bothers me lmao 