Is odd-numbered damage that’s halved then doubled the same value as before, or one less?

Let’s say there’s a Dust Mephit at full health that was hit by the Fireball spell and made the save. The damage on the die is low at 17, so the fire damage is halved. But, Dust Mephits are vulnerable to fire damage, so it’s doubled again. Does the rounding happen after the final total, and it stays at 17? Or does rounding down happen after each step, reducing it to 8, then double to 16?

Is Sneak Attack damage halved on a successful Will save if a Wand of Cure Light Wounds is used to trigger the Sneak Attack?

Suppose, a Rogue with Use Magic Device wants to attack an Undead, perhaps an Incorporeal one. They can use a Wand of Cure Light Wounds for that since it does require an attack roll. The Rogue somehow gets their Sneak Attack: the Undead is flat-footed, flanked, or something like that.

Now, the said Undead successfully makes their Will save and only takes (1d8)/2 damage, instead of just 1d8.

Is the Sneak Attack damage also halved?

Will an Incorporeal Undead halve the damage one more time because the Rogue is not incorporeal?

Is your maximum jump distance halved by grappling?

Here are the rules about Jumping :

Your Strength determines how far you can jump.

Long Jump. When you make a long jump, you cover a number of feet up to your Strength score if you move at least 10 feet on foot immediately before the jump. When you make a standing long jump, you can leap only half that distance. Either way, each foot you clear on the jump costs a foot of movement.

High Jump. When you make a high jump, you leap into the air a number of feet equal to 3 + your Strength modifier if you move at least 10 feet on foot immediately before the jump. When you make a standing high jump, you can jump only half that distance. Either way, each foot you clear on the jump costs a foot of movement. In some circumstances, your DM might allow you to make a Strength (Athletics) check to jump higher than you normally can.

Here are the rules about moving a grappled creature :

When you move, you can drag or carry the grappled creature with you, but your speed is halved, unless the creature is two or more sizes smaller than you.

I already know that jumping, say, 10ft up or forward with a grappled creature would cost 20ft of movement. But what I don’t know is whether your maximum long/high jumping distance is also halved by grappling.

For example, would someone with a Strength of 20 (normal maximum running high jump of 8ft) be able to jump 8ft up (using 16ft of movement) with a grappled creature, or would he only be able to jump 4ft up (using 8ft of movement) ? This assumes the 20 Strength grappler/jumper has made the running start beforehand.

Firefox youtube audio halved

I just noticed that playing whatever from youtube.com specifically, plays at less volume than it should be- the green bar in the volume mixer provided by the os appears to go only half as high compared to the same track played:

  1. from soundcloud.com (uploaded from the same guy);
  2. via a foobar2000 component, foo_youtube, that plays yt audio (same yt link), no gain applied as far as I know, and I apply no gain myself.

Setup:

  • OS: Windows 7 Pro
  • Browser: Firefox Developer Edition, 66.0b14 64-bit
  • Drivers/plugins/codecs: up-to-date, from what I can tell

Never mind the green bar, it’s an audible difference. I’ll supply any further information as requested.