Honestly I'd be a bit dissapointed if the combat was easy - BG could be notoriously hard sometimes (remember Lord Firkraag?) and I for one find it refreshing from smashing 1 rinse, repeat kind of combats (looking at you Geralt). It's rare nowdays that the game actually requires you to think (I especially loved the spider matriarch fight).

As for the temple I'm sorry to say but it's definitely a you thing - I took Shadowheart's word it's imperative we get there asap so I only stumbled upon Astarion trying to find the entrance and we 3 manned it easily straight from the nautiloid.

I think Sharp gave you a sound advice I'd just emphasize it's imperative to pay attention to positioning and react to the terrain, also you know you can step out of AOE effects like silence right?

Also there are surely going to be other difficulties available but they just want to fine tune classic first.