My question is, how well of a weekly routine is this? I also wanted to know, what kind and how much of cardio should I be doing a week? I read somewhere that doing high intensity interval training is great for getting tone, how true is that?
This way the upper back isn't pre-fatigued from shoulder work the day prior, and the bis/forearms are also fresh without being stressed the day before. Not really a deal-breaker though.
Also, all the cool kids train legs on Monday, not Chest.
Anywhere from zero to 5 or 6 hours a week, depending on goals. "What kind of cardio" is like asking "what kind of lifting". Super vague with lots of good answers, but no one "right" method.
If by "tone" you mean "fat loss", then HIIT can be great. But it's just a tool, like regular sprints, sled pulling, or walking, and you need to consider that almost any kind of cardio will influence your lifting and nutrition. Generally speaking, the higher intensity your cardio, the more you have to think about recovery time between training sessions.
you will get more out of your biceps workouts if you do them after some heavy compound lifts, because the big muscles. What exercises and set/rep schemes are you using?
I put forearms with back because heavy deadlifts will work wonders for your grip/forearms. and alse with legs because you are also moving a heavy weight and forearms often benefit from frequency (same with abs).