The answer to your questions will also depend on the time of year The availability of pollen and nectar.
In the spring during dandelion flow you can get away with doing just about anything. during a dearth in drought like conditions The bees will not bee quite as accepting.
"Then I read in other posts about robbing frames from one hive and giving to another to boost it?"
Nurse bees will be readily excepted they have not developed the guarding instinct or have oriented to their hive so they will stay with the new colony. It takes 2 to fight and because the nurse bees don't want to duke it out they are accepted. The nurse bees will be on frames with open brood, The more open brood the greater % of them will be nurse bees.
"Or swapping hive positions so returning bees go into the wrong hive to bolster a weaker hive?"
The returning bees will have honey or pollen loads and are looking for a place to store it a bee with food will not be refused entry and with a full stomach they are not looking for a fight either.
"Or shaking bees and skutteling a hive and letting the bees beg there way into another hive?"
I recommend smoking the hive to be shaken out heavily 3 times over 15 min before hand so the bees will have filled their honey stomachs first This I be leave will make them more desirable for the other hives to let them in. Either way the guard bees will let them in of turn them away. The fighting happens out side the hive if any/ away from the queen.
"So my question is why don't we have to worry about those bees killing " their " new queen in those scenario's?"
They can be but you can greatly reduce the risk by controlling there introduction.
"Can I take a frame full of brood AND bees and just put it in another hive?"
Yes but remember that a frame with mainly capped brood the bees on that frame will be older, could be more aggressive to the queen in the hive and those bees have most likely have taken their orientation flights so when they leave the new hive they will return to the old hive. In the end you will have moved a frame of capped brood and very few of the bees stayed with it. Either move frames of eggs and larva. Or brush the bees off the frame of capped brood back into the original hive and move the frame with no bees then shake a frame or two of bees off of a frame of eggs and open brood. These bees will stay with the new hive.
If there is a dearth Don't Try Any Of The Above... The bees will not be in the mood to play well with each other.
