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if i use golden wish to get a contraption into my hand and use master transmuter to put that contraption on to the battlefield will i be able to crank that contraption?

Any Contraption on the battlefield that wasn't assembled, immediately goes to the scrapyard/graveyard as appropriate.

Do Damping Sphere and cards such as Mana Flare or Heartbeat of Spring that add extra mana when a land is tapped for mana interact at all? Or that extra mana not considered to have come from the land itself? (I know the Oracle on how Mana Flare works has changed over the years)

The condition is "If a land is tapped for two or more mana"... which means that (a) you've activated a mana ability (b) on a land (c) that includes {T} in the cost (d) that would produce two or more mana.

The oracle text for Mana Flare is: "Whenever a player taps a land for mana, that player adds one mana of any type that land produced." So the mana ability on the land isn't affected, this is a trigger that adds an additional mana afterward. So, if you tap your Mountain, the mana ability of the Mountain gives you {R}, then Mana Flare gives you {R}, and Damping Sphere won't care.

Most of the effects like this are worded the same way... Heartbeat of Spring, High Tide, etc.

However, some are different... Mana Reflection is worded: "If you tap a permanent for mana, it produces twice as much of that mana instead." This is a replacement effect, so when you tap a Forest, the mana ability would attempt to add {G}, then Mana Reflection would replace that with adding {G}{G}, and then Damping Sphere would replace that with adding {C}.

Small addition: Mana Flare fails not only on (a), but (b), (c), and (d) as well. It is a triggered ability as mentioned, but it is not the land's ability, and the production of mana is a separate instance.

A side note as well. Since you are the controller of the affected object, you control the order of replacement effects. This wouldn't effect the above example (Damping Sphere + Mana Reflection). It would though, affect if you had two Mana Reflections. Upon tapping a Forest (G), you would first have to apply MR (GG), but could then choose to apply the other MR (GGGG) then DS (C) or the DS first (C) followed by the second MR (CC) -- end result being either C or CC.

You have Gideon, Battle-Forged on the battlefield. You activate his 0 ability to make him a Human creature. Opponent casts Moonmist.

1. Gideon transforms back into Kytheon? (Pretty sure I'm correct)
2. Kytheon retains loyalty counters, even though they're useless? (Pretty sure I'm correct)
3. Kytheon is still indestructible until EOT? (Not sure)
4. Kytheon still has prevent damage until EOT? (Not sure)

I'm pretty sure all the answers to those are yes.

1. Gideon is a human creature that is a double faced card. Just as Kytheon can transform, I have to presume Gideon can too.
2. Just like how +1/+1 and other counters stay, I'd have to imagine that they would in this case. Even if they're now useless.
3 + 4. I'm pretty sure that both sides are correct. In much the same way as a pump spell would remain after a card flips, an ability granting abilities and causing prevention effects should still work as they should.

I will note that I am not a judge nor do I have the rules in question specifically looked up. But I feel pretty confident that they all work out as they should.

The loyalty counters aren't 100% useless... normally Kytheon would die to Moonmist (as he'd transform into Gideon with no loyalty) but here because he still has loyalty counters, a second Moonmist won't kill him, he'll just transform back into the Planeswalker with as much loyalty as he had before.

And yes, all the continuous effects from the +0 will still apply. Until EOT, Kytheon will be a 4/4 with indestructible and all damage to him will be prevented. Also, any combat damage dealt by him will be prevented by Moonmist. All in all, not a lot of damage will be happening this turn.

Oh wait, so he'd be a 4/4 until EOT instead of a 2/1? That's cool. Didn't consider that.

And since Moonmist only prevents combat damage, I assume he could still damage things with a fight card and live through it.

i have a standard rotation question when Guilds of ravnica i think kaladesh block and amonkhet block will rotate but after that now that blocks are gone for now i dont know how standard will rotate in the future.

Have a look at https://whatsinstandard.com/ - it's a clean page that shows what sets are currently in standard, and when they will rotate out.

Short version is it'll still work the same way - each time the fall set comes out, a year's worth of sets will fall out of standard.