I'm certainly no expert on this, but from what I know:
Will our kids remember more of their childhood since their memories will be so strong?
Do you mean that by doing early learning activities we make their memories 'so strong' and therefore they would remember more from their childhood?
If that's what you mean, then I'm not sure the first premise is true in the first place. We certainly make them more familiar/knowledgeable in the subjects taught, and more intelligent (cos of brain stimulation), but whether or not overall memory is improved or not from, say, teaching reading, I'm not sure, unless you're doing memory-improvement exercises.
It would make sense that they would since they will remember the factual things. Anyone seen research on this?
Yes, of course they will remember more of what they've been taught the more you teach it, but that's not the same as saying that their overall memory ability has improved.
Mind you, I wouldn't be surprised if research shows that along with the increase in IQ, memory power also increases, but I just don't know about that.
Also, when can you tell that something is in long-term memory and not just short term? How long do things typically spend in short term memory?
According to Wikipedia:
Long-term memory (LTM) is memory that can last as little as a few days or as long as decades. It differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 18 seconds. Biologically, short-term memory is a temporary potentiation of neural connections that can become long-term memory through the process of rehearsal and meaningful association. Much is not known about the underlying biological mechanisms of long-term memory, but the process of long-term potentiation, which involves a physical change in the structure of neurons, has been proposed as the mechanism by which short-term memories move into long-term storage. Notably, the time scale involved at each level of memory processing remains under investigation.
As long-term memory is subject to fading in the natural forgetting process, several recalls/retrievals of memory may be needed for long-term memories to last for years, dependent also on the depth of processing. Individual retrievals can take place in increasing intervals in accordance with the principle of spaced repetition. This can happen quite naturally through reflection or deliberate recall (a.k.a. recapitulation or recollection), often dependent on the perceived importance of the material.See more here:
http://en.wikipedia.org/wiki/Long-term_memoryhttp://en.wikipedia.org/wiki/Short_term_memory