On point 4, on my omega dawn server we have Zombie Awareness, Primitive Mobs, Infernal Mobs, a heavily configured hunger overhaul and play on hard mode.
First few days is like vanilla on drugs. You really need to get yourself somewhere safe and establish a good source of food (otherwise it's zombie flesh for breakfast, and that does less for your hunger). Plus definitely don't go out at night (at first).
After that, we've found the big challenge is actually Rocket and Festive Creepers. Rocket Creepers take off and land and explode, while Festive Creepers actually launch TNT at you while keeping their distance.
All combined, you need to change your game style to deal with better AI zombies and mobs that can turn your base into a large hole in the ground.
It does slow you down at the start, and does cause some extra slowdown throughout the game as you need to think defenses and lighting. It's a pure survival change. Once past that, you'll still get the situation of amassing a lot of resources quickly.
Another thing we do is that the server has Twilight Forest, but you can only access that via Stargate mod (as server admin I place a stargate in the Twilight Forest and the diamond in pool portal is disabled for non-OP). So players have to build or find a stargate and fuel it first before able to go rape TF for its resources.