What is distinction between forms of address?

[Gene Linden]

What is the distinction  between the forms of address, i.e. Kära and Bäste.  Do they have the same meaning, and can they be used interchangibly?  Would one use the terms in a business letter, such as used in English, like:  Dear Mr. Smith:

[Stig Hansson]

Hi Gene
Kära is more familiar than bäste and the expression Dear corresponds to bäste. Please note that the ending a is feminine while and e is masculine. The a can also be used as plural.
Stig

[Anders Andersson]

Kära/käre is indeed what you would use within the immediate family or with close friends, although I'd say the word itself actually translates to dear or beloved. The word bästa/bäste suggests more of a business relationship (for addressing a customer, the kids' teacher, and so on) and translates to best.
 
The same distinction applies in closing the letter with Kära hälsningar or Bästa hälsningar (best wishes).
 
I have a copy of a Swedish letter-writing handbook printed in 1860 (Nya handsekreteraren by Ludvig Westerberg), demonstrating some very elaborate language that isn't used today. It looks beautiful, but I wonder whether those letters were always as sincere as the wordings suggest. Here is a sample:
 
11. Bäste Wän!
Jag beswarar din wälmenta nyårsönskan med samma kärleksfulla tänkesätt, hwari du yttrat den i ditt bref. Du har wäl förekommit mig dermed; emedlertid fruktar jag icke, att du derföre skall anse min wänskap för dig mindre warm och uppriktig, än den werkligen är. Din tillgifwenhet utgör en wäsendtlig del af min lefnads sällhet, och din ständiga wälgång är således min ifrigaste önskan. Måtte din lott motswara mitt hjertas redliga önskningar! Förunna mig äfwen hädanefter din wänskap, som hugnar och gläder mitt lif; ty näst önskningarne för din wälgång, hyser jag ingen warmare åstundan, än att intill döden förblifwa
Din hjertligt tillgifne etc.
 
Note also the archaic spelling (e, f, h, w) and words (sällhet, hugnar, ty).

[Harriet Boquist]

Hallo Gene
 
I?ve seen that you are related to Klas Fredrik Snäll.  
So am I!!
He was my Grandfathers Grandfathers son. Have you found any other living persons, in Sweden or anywhere else.
I don?t have so much, unfortunally.
It would be great to hear from you via mail.
Best rgds
Harriet