Topic: AC Adapter usage affect battery life

I have a a few specific questions about having the 3DS plugged into its AC adapter for extended use. I have a read topics related to my questions, but they do not provide an answer specific to my question or they have conflicting opinions. Sorry for bringing up this topic again but like I said I have not found, in my searching, a good hard response.

1) Will playing on my 3DS for extended use, while it is plugged in with my AC Adapter, shorten the life of my battery?

I do not intend to do this on a perpetual basis; I do bring my 3DS out often for Street Pass and for the Activity Log. My idea is to alternate; play on the go and then play for an extended time at home while plugged in with the AC Adapter.

2) Is it harmful to plug in my 3DS for extended play with an AC Adapter when the battery is only partially discharged (Like 75 to 50% percent remaining) ?

I have read and understand the Lithium Ion batteries do not develop 'memories' like NiCad batteries. However what I want to know is if constant, I guess, 'premature' charging shorten or harm the battery life in some way?

Thanks in advance

3) a '?' at the end of your thread title would have been appropriate