None of those images come from within games. The first image comes from Sogna Digital Illustrations 1. The second is promotional artwork for the Digital Illustrations 2000 series (but that image itself isn't contained in any of the three.) The third is the CD insert/cover art for Viper Island Vol 3.
There is no sequel to GTS (in so far as Sogna canon is concerned.) The first chapter of
The Devil Came... story is told in V6 and V6 R, and the second part in GTS (the game, OVA, audiobook, and Viper Limited novel all seem to tell slightly diffferent versions of this chapter.) There is no third part.
Yes, there are a few scenes featuring Asuka and Miki in Typing VIPER and the Paradice series that don't come from V10 or CTR.
Galactic Guardian Guynarock is an old PC98 game made by the folks who created Sogna when they were a gamehouse named M.I.N. A couple of times during their history, Sogna tried to diversify their library beyond the VIPER series games, and Galactic Guardian Guynarock R (R for Remake) was the first attempt (and the only serious one.)
Gu
nyarock is a fictional game. Raika has made it her life's pursuit to acquire a copy, though she never will because its never in stock at EBGames (or anywhere else for that matter.)
Your "soundless" BTR version is likely set to MIDI and you don't have the Anex86 MIDI plugin. From the main BTR menu, select the last option to go to the Options submenu. The fourth option on that menu is audio output. The first option on the next menu will let you toggle between FM and MIDI audio. If you still don't hear anything after setting MIDI mode, close the emulator window and go into Anex86 Config, look at the MIDI tab, check the two checkboxes there and retry. Consult
this post for more information.