I don't think anyone loves the PKs to resolve a match--most people hate it, but think it's better than the alternatives. By the end of 120 minutes, everyone on the pitch is exhausted, so playing longer isn't a good strategy. Over the years people (and minor and recreational leagues) have toyed with other systems, like removing players every few minutes (which is what they do in world 7s, I think, but a smaller field there, which makes a big difference). All of them end up being pretty arbitrary ways to end a well contested game. I also wouldn't mind implementing a golden goal in extra time, which makes sense in low-scoring games, but less so when a match heads to ET tied 3-3 or 4-4, etc. Of course, most soccer games are low scoring, at least at the higher levels.
As for the offside law, it's an interesting theory to use the hockey system. I'm thinking through how difficult it would be to implement. Using the lines already on the pitch, you could make it that the players must be onside before crossing the 18 (the penalty area), but once the ball is across the 18 without an offside, no offside between the 18 and the goal line. But the way passing in soccer works, that would be too small a space to really implement it. Maybe a new 35 yard line?. I'd be curious to see someone test that for a season to see how it impacted play. It would bring a dramatic change to how team defending works. Currently, defensive strategy is designed with the offside law as it is, so this would be a dramatic change.
The offside law really isn't that complicated (compared to, say, pass interference and what is a "catch"), but TV announcers don't make an effort to understand it, so they misinform people on a regular basis. American TV announcers are generally terrible about how the laws of the game work.