First books I bought on bulldogs too, think I paid £25 for world of the pit bull terrier. Best books for me were probably wildside kennels and California jacks, all long gone. Stratton also wrote books on Oscar's (aquarium fish) had them too.
No, I always shoot to the same anchor so measure how many X's the elastic elongates and cut to length. Some brands of elastic I shoot shite with though. Red shot for one, sniper sling yellow spot on.
90mm seems right for me, the best I've ever shot was a uniphoxx with light bands (87mm?). Too small and no good for hunting though. Struggle with tubes too. Prefer clips now too.
PPMG? Had one years ago without clips, too wide for me and fork hits make a mess of the Ali. Saw a video of gkj using his, excellent shot, catty was covered in fork hits too.
At the minute I mostly use the Leighton's catty (multi coloured) with 9.5 lead and yellow.8 ss 24/12 accurate and kills stuff. 90mm seems to be my width, I shoot ttf well but don't like it as much.