What are the rules for upgrading existing magic item?

This question comes from the comments on my previous question.

In short, if I have for example a Belt of Incredible Dexterity +2 (4,000 gp), and I want a Belt of Incredible Dexterity +4 (16,000 gp), can I simply go to a wizard and pay the difference and wait for the necessary days to have the item upgraded?

In this case, since the cost goes from 4k gp to 16k gp, I’d have to pay the wizard 12k gp and wait 12 days, while s/he would have to spend 6k gp to perform the task and keep the other 6k gp as profit.

However, the only example I found in the rules, is of a wizard upgrading his/her own item:

Example: Patrick’s wizard decides to use his downtime to increase the armor bonus on his bracers of armor +1 to +3. The price difference between the two types of bracers is 8,000 gp, so Patrick’s wizard must spend 8 days and 4,000 gp (half the 8,000 gp price difference) upgrading his bracers’ magic. If he has fewer than 8 days before the next adventure, he’ll need to finish his crafting while traveling or use accelerated crafting in town to speed up the process.

Is there an overview of rules differences between various editions of Tunnels and Trolls?

There are several versions of Tunnels and Trolls available, with a good deal of variation in the format between them. Is there a good summary of the changes between the different versions?

(I’m especially interested in the more modern releases: 5.5, 7, The “alternate” system from 7, 7.5, 8, and Deluxe.)

Are there any specific rules about how to prepare spells?

[This question is related to my Dwarven Cleric character.]

In the Player’s Handbook, it says that all spells need to be prepared in advance before they can be used. I get that this is done while resting but does it matter how long the rest is (i.e. long or short) as it doesn’t seem to say how long each spell takes to prepare.

Also, are there any specific mechanisms for preparing spells, other than telling my DM "In this rest I will prepare X spells"?

Are there any rules for the creation and forging of Electrum?

Are there any specific rules for the creation of electrum? I have found some sources saying it was naturally occurring in some editions (as noted in the forgotten realms wiki) but I haven’t located anything specific for artificial creation, or enchantment. I’m happy to cannibalize old editions for good ideas, but I’m not sure if anything actually exists.

What are the rules around retrying failed scry attempts?

The rules for Scry state that.

On a successful save, the target isn’t affected, and you can’t use this spell against it again for 24 hours.

However this seems a bit ambiguous. Can that player not use the spell or the party? Does the source of the scry matter?

For instance, a party who have a scrying eye magical item. A Scrying Eye is an item that allows a person to cast the Scrying spell for up to ten minutes at a spell DC of 15. It can only be used once per day, and then cannot be used again until the next dawn.

The item is based off this crystal ball

The typical crystal ball, a very rare item, is about 6 inches in diameter. While touching it, you can cast the scrying spell (save DC 15) with it.

I have lowered the spell DC from the original to account for my item not requiring attunement.

and 2 magic users both with Scry.

If player A uses the scrying eye and fails, can they then cast scry themselves again as it is in effect the item that cast the spell and not the player? Can player B also attempt to cast scry?

Can feats like Psionic Weapon, Shot or Fist work with out interference with Path of War Rules?

Can feats like Psionic Weapon, Shot or Fist; or Greater Psionic Weapon, Shot or Fist work without interference or sacrifice with Path of War Rules?

Effects from stances remain so long as stance is not changed. Gaining and using focus* during a rotation of Boosts, Counters and Strikes is what I worry about. With Psionic Meditation you can gain focus with a move action, but can I expend/use said focus at anytime during when a boost, strike or counter happens?

* see the “Gain psionic focus” part for the rules

Does carrying/dragging a willing/unconscious creature cause half movement as per the grapple rules?

When you carry/drag an unwilling creature that you have grappled, your movement speed is halved.

Is the same true when you carry/drag a willing or unconscious creature (ex: move your friend out of danger) ? Or in other words, a creature that does not resist against your attempt to move it ?

(This assumes that you have a good enough carrying capacity to easily carry/drag an object of the same weight as the creature you wish to move)