VF-1S: Four Head Lasers
VF-1J: Two Head Lasers
VF-1A: One Head Laser
Roy was the leader of Skull Squadron and piloted a VF-1S. In Macross: Do You Remember Love his VF-1S was equipped with fast packs, boosters, and a strike cannon (this is the double barrel cannon you're referring to). Hikaru pilots a VF-1S in DYRL as well which is also equipped fast packs, boosters, and a strike cannon. Hikaru, Max, and Kakizaki all piloted VF-1A's in their respective colors with fast packs and power boosters in DYRL; these three along with Roy made up Skull Squadron. There are also several cannon fodder VF-1A's, the tan/beige fighters in DYRL and the TV series. These were given the name cannon fodder because they are always seen being blown away by enemy fighters.
In the TV series, Hikaru piloted a VF-1J Valkyrie Figther. He later piloted Roy's VF-1S after he was killed in battle. Max and Miria both pilot VF-1J's in the TV series as well, while Kakizaki pilots a VF-1A.
Bang for your buck, the 1/48 VF-1 fighters win hands down. I was in your shoes towards the end of January earlier this year. Be warned that if you buy one you will no doubtedly want more. I started out looking for a G1 Transformers Jetfire figure, and now own every 1/48 Valk made by Yamato along with a few customs. It's very addictive!
Make sure you look for second edition releases. There are subtle differences in the releases. I'll let someone else explain those to you.
You will find the guys around these parts most helpful. I'm the leader of the Ballchinian Brigrade and will answer any questions I can; understand I still consider myself a newbie at all this too. I've only been collecting since late January.
Welcome to the forums!
OO