thats bg1 you're referring to about the nashkell mines, anyway, bg2 didnt got you lost but this does? :O i found this way easier than bg 2 and I played it bg2 recently ( solo granted but still ...)
Only worry about quests that really seem urgent as in the right then , those you can usually fail , rest can be delayed quite a bit , or they can get updated with other related quests when you reach a certain point...
Maybe your troubles stem from an unproper build of character? don't spread too thin on the skills, attributes, remember to save points for the level 2 ( need 2 skill points) ,3 ,4 etc if you don't have a mage in the build of your 2 characters you might feel it hard at the beggining , specially since higher level mobs give you a dent in your hit chance, , use a bow/elemental arrows they dont cost you skill investment if you need a quick environmental control...
Hybrid builds are usually very usefull with only 8 int and a point in most mage schools for buff spells (since they always get a 100% success if they are skill level 4 or under ). Later on you might need the int to equip a good sarong anyway but investment is not that necesarry... go crafting section and see what you can craft with the stuff from the traders and get some rings, amulets ,belts asap
The spider summon from geomancer is pretty good from the start of the game to the end and it's not hard to aquire ...
( MINI-SPOILER 2 extra companions you can get from talkin around in cyseal ...The summon is per character limited so 4 members = 4 summons if you are having so much trouble)
STEAL STUFF and dont get caught, go sneak mode (even if you dont have any point in it) and to decrease gettin caught and to reload so often , get another character into chat mode with the npc's that have their view oriented at the prize you wanna get
Save, reload before you enter the barter menu on the skillbooks traders till they have the skill books you want...(give a search on the wikia to see what kind of skills you can learn if you dont want to keep it a surprise and to better build yourself towards what you want)>>> remember this only applies each time you level up, if you see the barter then save , the inventory wont refresh, you have to level up again or advance on the main story( or leave your pc on for a night , it worked for me hehehe...)
There are plenty of tools to play this game in various ways, you can shoot yourself in the foot to make it harder but not impossible , good luck

and have fun experimenting different strategies/builds
(MINI-SPOILER you can respec your main characters later in the game)