2 quick and easy questions

Well was jsut curious on two things.

1. Is 20-30 mins cardio everyday enough?Just looking to lean out some, not a quick fat loss program. Mainly if its 20 mins, its on the treadmill. At a pace of 3.8-4.1, and raising the incline 3% every 2 mins.This treadmill goes up to 30%, (my knees are actually touching the heart rate grips). If its more the 20 mins, i switch it up, maybe 15 mins on stepper (fat loss option) the go to the treadmill or switch to a bike.

2. I know everything about muscle confusion and keeping up with new workouts and switching your routine. But have never seen anyone try this, so was wondering if its not a good idea. Basically im running one body part a day. So why couldnt i on week 1 of chest do high reps, low weight. Then for week two of chest run low reps high weight? It would always keep your muscles guessing wouldnt it? i would do this for every body part.

Thanks guys for the help.

Age: 31
Weight: 180
Height: 5-9
Bf% 14-15% ( educated guess, havent tested in about 6 months)
Experience: 2 years seriously

bump?? i didnt think they were that stupid of questions

1. Generally cardio is best done on empty stomach first thing in morning or 45 minutes after drinking whey shake if concerned about muscle loss. Or many do after weight training since muscle glycogen has been depleted and in a better state for fat loss to occur.

2. that is actually a pretty common strategy. You can go with that, many do