Smancer, sorry I didn't explain for how long I've been playing, I have been playing since around mid July, but the thing is:
I have been playing /players 8 for mostly of normal and nightmare, can you change it on that private server? if you play like this, you get lvl 18 in act1 normal with ease, lvl 24 on act2 normal, and I wasn't doing full clears!
When things got hard, all I had to do was to go back to the place with p1 (/players 1) and because I was so high level due to p8, things went smooth again.
In Hell, things change. Even on p1 it takes a lot of time to kill the monsters, so I stopped the Fishymancer on Hell Act 1. Started the sorceress, it took forever to kill on p8 so I played her for a long time on p1, focusing on fireball(made a Leaf runeword as soon as I could), then on normal Act 4 I got the frozen orb(lvl30), that was when things got much easier, with some points on frozen orb and some in cold mastery I could play p8, and all Nightmare I don't remember seeing cold immunes, so I got the sorc to Nightmare act3 and since the Sorc is a lot faster(teleport) than the necro, I runned Night Meph a lot of times, got some Items, then I saw somewhere that Shako and Maras would not drop from him, so I went to Hell act 1, killed Andy, than I used one respec to only fire, and was doing Andy runs all the time(lots of deaths made it frustrating) but there was some nice drops once in a while, some unique amulets and rings but no Maras and no SoJs, 2 pieces of the IK set(gloves and maul), no shako, no arachnids mesh, no occulus, so thats when I saw your post and I felt like your questions were mine, there's a lot of guides but they sometimes aren't noob friendly, except for the fishy, but the fishy was really slow in Hell...
but with the Items I found I now had lvl 31 Raise skeleton and lvl 31 skeleton mastery, and you can buy a staff with teleport for the necro, so now I was able to finish Hell really fast. but I still haven't found the Items I'd like to have, guess I'll respec the sorc to blizzard and try Meph runs like pharphis and felixbavaria recommended.