There is a rules Q&A on the site, it has some added functionality like the ability to choose an answer and is frequented by some highly knowledgeable users so your question will get answered and the answers will be double checked by the other knowledgeable users. I'm sure one of the mods will move the thread soon.

You seem to have a couple of misconceptions here, so I'm going to try and address all of them in a way that makes it easy to understand what is going on.

Once targets are chosen for a spell or ability the targets will not change (unless another spell or ability instructs someone to change the targets). If, when a spell or ability resolves, none of the declared targets are legal (this could be because they no longer exist) the spell will simply fizzle.

Spells and abilities resolve one at a time in "First In, Last Out" (FILO) order and there is a round of priority when new spells or abilities can be added to the stack between each object resolving.

Once a spell or ability starts to resolve it resolves completely before anything else can resolve.

If a card changes game zones and then returns to a previous zone, it is a new game object with no relation to its previous existence.

Using card names to make this easier to track what would happen in the scenario you are asking about:

An opponent casts Murder targeting your Gutter Skulk.

You cast Undying Malice targeting Gutter Skulk.

Undying Malice resolves. (FILO order)

You sacrifice Gutter Skulk to Ashnod's Altar to make mana.

Delayed trigger created by Undying Malice goes on the stack.

Delayed trigger resolves returning Gutter Skulk to the battlefield. (FILO order)

Murder attempts to resolve and fizzles because none of its declared targets are legal. (Spells can't retarget without an effect changing the targets; Gutter Skulk on board has no relation to the gutter skulk that was targeted)

Replacement effects (which is the type of ability that all three of these are) do not trigger and do not use the stack. They simply change the outcome of a game event and can only apply to a given event once. Since you are the affected player you will get to choose the order in which the abilities apply.

Assuming that you want as many tokens as possible the optimal way to apply the effects is going to be PT & CotPP (in either order) and then AM since this will turn the clue into 2 clues and a food and then those three will be replaced with a food, a clue, and a treasure each netting you 3 each of food, treasures, and clues.

AM and then PT & CotPP (in either order) will result in 2 food, 1 treasure, and 2 clues. The upkeep clue turns into one of each token and then an additional clue and an additional food are added.

PT, AM, CotPP results in 2 food, 2 treasure, 3 clues.

CotPP, AM, PT results in 3 food, 2 treasure, 2 clues.

"Fox Jace" is what my entire comment was based on. I hate Jace so much and Furry Jace is no exception.

Yes, you get a drake.

Triggered abilities trigger any time their condition is met. When the Sygg trigger resolves you will draw your second card in a turn and the Alandra trigger is met and will be put on the stack the next time a player receives priority.

There is one card to be careful of with Alandra, Sky Dreamer, but as long as no one is using Day's Undoing; you will always create a taken if you draw 2 or more cards in a turn. (I have some 9 year old gripes about changing rules, but that is beyond the scope of this thread.)

Fursonas for your favorite characters. (and least favorite too.)

Yes to all.