I don't have VR to test so i can't guarantee that everything works properly, but people say it works.
There was an issue with MCM getting stuck on Skyrim Unbound after the start but it should be fixed now.
It was reported that VR Keyboard and SkyUILib VR Patch are required to use the Save Preset option, since without them you can't type in the Save Preset text input window (which uses SkyUILib).

Yes, because SUR doesn't include any SKSE plugins. Make sure that you use the correct version of SKSE for your game version, though.

No, you guys ain't got no SKSE and SkyUI, which are hard requirements for this mod.

No.

No. Please.

No, they now have huge differences so it's not safe and can cause bugs.

I don't really know what's safe or unsafe. It's better not to update anything on an actual playthrough anyway. If you're a risky guy and love danger, you can update but not to versions to which i put "New game is required when updating" or something like that into the file description on the Files tab, these versions will likely cause issues when updating midgame. It's also recommended not to keep saves created before the start created on older versions, better start a completely new game instead, because starting options that were changed in the update may work incorrectly after updating.

No, it would require compacting FormIDs, but some FormIDs are referenced in the edited vanilla scripts.

Yes, change the Dragonborn option on the first page of the MCM.

No (no, i don't plan to add it).

To get no weapons, uncheck Random and don't enable any weapons (all must be set to Nothing).
To get no armor, set Armor Type to Nothing.
To get no items, set Wealth to Nothing. (some other mods can add their items at the start, though).

You can't start it if you're non-dragonborn - Frea never appears at Miraak Temple and the cultists never come for you.

At the beginning of the game they are nowhere to be found, but during The Jagged Crown quest you encounter one of them (depending on the side you choose) as usual, except that he won't say that he knows you.

With SUR, Durhneviir won't be resurrected if you can't learn shouts.

Instead of the completion of the Dragon Rising quest, The Whispering Door now requires your relationship rank with Balgruuf to be >= 2. You can gain it by competing the prerequisite quest/quests (that are set in the MCM) for the Whiterun thane quest.

Most mods can be set up at any time and don't care if your character is completely created or whatever. Some mods require your character to be completely created since changing race resets some things, it should be safe to set up them in the starting room after you close the character creation menu for the last time. Though such mods usually prevent you from enabling them until the required conditions aren't met.

Note that it's recommended not to keep saves created before the start on older versions and start a completely new game when you update SUR instead, to avoid possible issues with the game start, so better use MCM Recorder, Setting Loaders and MCM presets where you can instead of creating one save with all the mods set up and using it your whole life.

Data\SKSE\Plugins\SkyrimUnbound\Presets (If you use Mod Organizer, see this directory in your overwrite folder)

A .json configuration file SKSE\Plugins\SkyrimUnbound\SkyrimUnboundBalance.json allows to change the balance of randomization such as random counts of items. It's only used if PapyrusUtil is installed and working. You can open it via any text editor including Windows Notepad and edit the values.

"bounty" : [ 250, 2500, 60 ]
This is the default auto bounty. The first value is min bounty, the second one is max bounty, the third one is the chance of a bounty in percents, i.e. the default settings given you a bounty between 250 and 2500 septims with 60% chance.

All other values control the randomization of starting items and follow the same logic:

• Each item group has 4 lines in the config, which represent the Wealth set selected by the player or randomly. 1 = Beggar, 2 = Poor, 3 = Medium, 4 =  Wealthy. Potions are an exception, since they're disabled for the Beggar set.
• Each line contains an array of 2 or 3 values. The 1st one is the minimum number of items, the 2nd one is the maximum number of items, the 3rd one is the minimum number of items when that item is set to Enabled in the MCM by the player (SUR increases the minimum number in this case to better meet the player expectations).
• The third one is optional and can be removed if you don't want to increase the number of items when these items are set to Enabled.
  

Spell addons are in Data\SKSE\Plugins\SkyrimUnbound\Addons\. To remove an addon, delete its file from this folder or remove the contents of the file. The order of the addons can be changed by renaming their files (in any way you want).

See Creating Addons for Skyrim Unbound Reborn.

If you need to run something after the character creation, you can check if the player controls are enabled. An example is my Choose Your Starting Skills. It will be triggered after the teleportation If you select "Continue", or after you click "Stay here". This method won't require any dependency on Skyrim Unbound.

You can also check the stage of SkyrimUnbound quest. In addition to stages 10 and 100, i added 20, 30, 90 in Skyrim Unbound Reborn:
10 - Skyrim Unbound is started, the player isn't teleported to the starting room yet (except the QuickStart mode);
20 - the player is teleported to the starting room, the character creation menu will be opened soon;
30 - the player selected Stay Here after the character creation and stays in the starting room (skipped otherwise);
90 - the player leaves the starting room, the fade-out plays;
100 - the player is teleported to the starting location, the controls are enabled.
To avoid adding Skyrim Unbound as a master, you can use Game.GetFormFromFile() papyrus function.

Alternatively, you can check if the player is in HelgenLocation: both Helgen and the starting room have it set as location. This method is NOT recommended for mod-added menus that pop up on game start, since SUR can't control this to delay these me

There are also SKSE Mod Events available:
SkyrimUnbound_OnAddonsLoaded
SkyrimUnbound_OnItemsAdded - called every time starting items are given.
SkyrimUnbound_OnPlayerTeleported - called when the player is teleported to the starting location.
SkyrimUnbound_OnAdventureBegun - called after the player is teleported to the starting location when all necessary preparations after it are done.
SkyrimUnbound_OnControlsEnabled - sent: 1) after Stay Here. 2) same as OnAdventureBegun if the player didn't choose Stay Here.
SkyrimUnbound_OnControlsEnabledAfterRaceMenu - sent: 1) after Stay Here. 2) if the player has choosen Stay Here, each time the player closes racemenu after choosing Open RaceMenu option from the actions in the starting room. 3) same as OnAdventureBegun if the player didn't choose Stay Here.
For mod-added menus that pop up on game start i recommend the last three and don't recommend OnPlayerTeleported.
Use example:

See Patching conditions for Skyrim Unbound.

I don't plan it.

I don't plan it