There's a few more sources of physical resistance now. Basalt Flasks, Chaos Golem, maybe some ascendancies, and you can get damage reduction from the new Kintsugi unique (which has lousy evasion for an evasion chest piece tbh and doesn't give you dodge like Hyrri's Ire does or large piles of movespeed like Queen of the Forest can) and fortify condition. Generally you should also sport some endurance charges and a high amount of life to avoid oneshots. Or you could actually attempt the armor/evasion hybrid, in which case you should probably wear The Brass Dome as your chest piece (because it has a ginormous amount of armor and you will never take extra damage from crits, but it nukes your block something fierce). Juggernaut Marauder gets double armor from chest and +1 endurance charge, so he's a candidate, especially if you combo Juggernaut with Veruso's Battering Rams for shock and stun immunity, but Trickster Scion and Trickster Shadow get 20% more evasion chance with the right setup, saving a ginormous amount of evasion.
Overall though physical spells are your achilles heel because once they hit they will hit hard. You can spelldodge and spellblock them down though. The build I mentioned above should dodge/block 91.5% of spells. I think you can do crazier with Vaal Grace and Anvil amulet, capping out at 94.5% chance of dodging/blocking spell hits. You can also wear Belt of the Deceiver for a nice damage boost (intimidated enemies take 10% increased damage) and reduced crit damage to mitigate the risk.
If you're dedicated to running around with Basalt Flask all the time (which is more a thing for CI builds than evasion builds) I think you can break like 50% physical reduction with just 4 endurance charges, a chaos golem, and those flask effect nodes the witch gets. On the other hand you can get a shitload of evasion with a jade flask so if you're going to keep one flask on all the time as an evasion build, you might want to cap that evade chance.
No. You can break 8k hp with an evasion build, and you should generally invest health to avoid getting oneshot. The trouble is just that most people who play evasion are idiots and probably softcore idiots at that. In hardcore everyone understands the importance of stacking life or energy shield. You can also just cap your ranged evasion chance and play a CI Trickster Shadow as detailed above. That way you can enjoy a fuckhuge pile of ES behind your evasion, since it is possible to cap ranged evasion chance without any evasion gear (other than a Jade Flask of Reflexes) this way.
The easiest way is to just play a Necromancer Witch and self-buff with Bone Offering. Maxing dodge and block as a Necro Witch can be a joke. Other than that Reckless Defense + Saffel's Frame (You can use Anvil or Stone of Lazhwar for more block, but you'd lose out on Hinekora's Sight that way). This sacrifices your ability to block attacks which is fine with giant piles of evasion evasion + dodge in exchange for better max resists and spellblock. You could also give up your weapon slot for an Advancing Fortress (+50 life, +110 evasion, +15% block chance) but you might want to do damage with that slot. Reckless Defense is fine when you have huge piles of evasion, dodge, spelldodge, and spellblock because the odds of anything managing to crit you will be stupidly low anyway.
If you have good dodge from gear and increased aura effect, you can just skip the Acrobatics and its penalties and use Vaal Grace to top yourself off to 75% dodge and spelldodge.