Hi!
First of all: Cool

Answers
A. I would guess you mean Skavsta?
http://www.skavsta.se/en/ and that would be buss.
http://www.skavsta.se/en/content/2/34/by-bus.htmland that buss leaves Skavsta at 12:40 and you´ll arrive in Stockholm at 14:00 and then it´s really easy to find Centralen at from there you´ll take the tube to Mariatorget and ca 3 minute walk to Rival.
Also check out googlemaps before so you´ll find it, try these words "Sweden, Stockholm, Mariatorget"
And you´ll notice Rival and Mariatorget and heads up for the circle with a T in it, that´s the subway!
B. No, or shall i say: Who knows, otherwise you´ll can buy a ticket at the entrance and since there´ll be more that 300 tickets, you´ll be fine. Otherwise the staff at Rival will find you a place nearby who can help you with tickets! Don´t worry about that!!!!
C. Conny wrote somewhere that they will be releasing a single in March and the album in April, but who knows???
If, you´ll be staying an extra day and want to shop some Electric Boys CDs, you can go to Bengans at Drottningatan 20. But since you´ll be staying in the "Soho" part of Stockholm there´ll be a couple of used record stores to endulge in.
See you there
TM