1) I ran it a long time ago and I remember it turned out to be quite a drag go through the dungeon. If you like old school slow dungeon crawling it'll be ok, otherwise if you prefer a faster pace, consider fast-forwarding the exploration of corridors and go straight into the rooms, and make navigational choices a bit more colorful like "do you choose to go where the reddish light is coming from, or where you feel the cold moldy air?" to avoid saying "left or right?" every time.
2) If you run it at low level, I personally like monsters with ONE special ability, so that they aren't simply doing danage but the players also don't have to face much complexity. Examples could be mephits and shadows. Also, you can replace a monster encounter with a complex trap that needs thinking instead of rolling.
Side note: I don't like adventures having placeholders rooms and telling you to choose what to put there, because if I buy an adventure I expect the author to do the job for me, and IIRC B1 was one of those... I actually left most of them empty because I prefer less densely populated dungeons, but if you have many monsters ideas to try you can actually take advantage of them.
