Next to the setting icon, there is a button with a question mark. This is the "how do I play this game!?" menu. You should be able to find a video called "window", wich tells you how to jump over a window. You will be impressed to findout you can also do that on some other props too.

Also, when a bomb isn't accessible, you should try to let me know where instead of making me find the one that doesn't work, and no I haven't found any bombs that can't be defused.

Can't access bombs and trying to get wall charges in the right spots doesn't make it feasible either

the "explosives are hidden" part was not a problem itself, but when you have to use a breach charge on a wall just because there is a barrel that blocks your way to the door and that causes you to blow up the entire map because surprise surprise, there was a bomb in there gets annoying real fast

You can get to all the places you need to. If you can't, you either need to find the right angle to be allowed to jump over the prop.
For the part where you don't know where the bombs are, you have to find them. It's part of the challenge.

props are blocking a significant amount of ways to enter places, making them unreachable without explosives...and this is a Bomb Defusal mission with several bomb in unspecified locations