The difference between them and them all is usually just a way of making it clear that the action applies to all of the elements within the collective noun or group, and not just to some (but not all) elements of the group, or the group noun itself.
For example:
When my friends came over for a party, I cut them all a piece of cake.
In this sentence, a piece of cake was cut for every member of the collection "my friends" - i.e. each of my friends was given a piece of cake.
If we had chosen "them" instead of "them all":
When my friends came over for a party, I cut them a piece of cake.
We leave ambiguous the possibility that I cut a single piece of cake to be shared by the whole collection (i.e. one piece shared between all of my friends).
Similarly,
When we went to the pond to see the ducks, we gave them all some bread
implies that the author gave bread to each of the ducks at the pond, contrasting with
When we went to the pond to see the ducks, we gave them some bread
where it is possible that the author only gave bread to the collection of ducks as a group, and that some of the ducks in the group may not have been given bread.
So in summary, them all tends to be used where the author wants to make it clear that the action applies to each member of the group, whereas them can also refer to the group as a whole without specifically referring to each member of the group.
Increasingly the use of "them all" is becoming deprecated in favour of "each of them". Consequently, if you're not sure, use this form:
When my friends came over for a party, I cut each of them a piece of cake.
In your first example, you would just use above, as an adverb is all that is needed. But it really only describes what is directly above.
In your second example, from above is not helpful because it is not specific as to what you are referring to. You should point to the specific location.
When using from above, from is a preposition, so I expect an object in that phrase. For example:
From above the trees, I could see the distant horizon.
The locations are specific. Also motion is often involved:
The birds flew from above the trees to the roof of our house.
There are some idiomatic usages though, for example:
Their new baby was a gift from above. (meaning from heaven)
Best Answer
They are different words with different meanings, except in colloquial language (slang), where they are often used interchangeably.
1) Usage of 'them': it's the accusative form of 'they' (3rd person plural) so use it in sentences where a 3rd party (someone/some people separate to 'they') is doing an action to 'they'.
Usage of 'these'/'those': they are demonstrative pronouns - the plurals of 'this' and 'that' - so use them to demonstrate something. 'These' is used for items that are in some way closer, more related, or in another way are the more important items of a sentence.
2) Examples of 'them': "John was asked what he thought of them."; "After I gave them a detention, I told them that they weren't making enough effort."
Examples of 'these'/'those': "Why are you trying those shoes on? These ones are much cheaper."; "Those people are silly, these are clever."
Hope this is clear enough and helps! If it does, an upvote and/or accept wouldn't go amiss!