Now here is a very specific question for you judge-types:

Let's says Groot is vacationing on beautiful Krakoa, sitting in the hindering, sipping a mai-tai on one of his Colossal clicks:

FLORAL COLOSSUS SPROUT: Non-optional. Groot has the Colossal damage symbol, a range of 4, and can't be moved.

And some noisy tourist comes along and rolls a 5:

On a result of 5: SHIFTING FOLIAGE. Printed hindering terrain acts as blocking terrain instead until the beginning of your next turn. Characters occupying those squares take 1 unavoidable damage and are placed in the owner’s starting area.

Groot takes the damage, but is he placed back in the owner's starting area?

As often as I field the Grootster, I promise you this will come up. Probably next week!

Looks like he's placed, not moved, but I could be wrong.

Place =/= move.

Groot can be placed.

If Nightcrawler can place him then I figure this can too.

Can nightcrawler place Blob though?

But wait - there's more.

Suppose Mr. Groot is carrying his Camouflage Card (feat) and is sitting in square G14 of Krakoa Island. Is G14 adjacent to H13 thus prohibiting noisy tourists from targeting him with ranged attacks?

Nothing prevents Blob from being placed.

Sure. Is there any specific reason you would think Groot wouldn't be adjacent to H13?

I just get a little fuzzy on the diagonal adjacency rules.

Are giants adjacent to walls, blocking, or hindering terrain from 2 squares out?

Please quote the game effects in question.

Giant Size
(NON-OPTIONAL) This character can’t be knocked back, and ignores Plasticity. When this character is given an action that includes a close combat attack, it treats other characters up to two squares away as if they were adjacent unless blocking terrain, elevated terrain or a wall would otherwise block the line of fire. This character can make close combat attacks against elevated characters, even when this character is grounded. Characters with the symbol do not block line of fire to or from this character. This character and a character on elevated terrain draw line of fire and make ranged combat attacks against each other as if they were both elevated, but terrain effects still apply normally. This ability can’t be countered.

Terrain of any type is not a character.

Also note in the passage that normalview quoted that the 2 square adjacency is only there during close combat, which is not happening.