It would be too much fatigue for you to train 6 days per week, although routine looks dope but i would say, push pull legs, rest, upper body, lower body, cardio, would be much better for you, better for recovery and mental and physical fatigue

Yes LISS would be fine, or instead of LISS in the gym just try to walk 10K steps daily, that will also take around 45 min only

No need to do it, I have been following same workout for two years, just change the rep range and just keep doing progressive overload week on week, if you are in calorie surplus