I'm readying up to start seriously following simplefit and have a few questions. Basic stats: I'm 29 years old, 173cm tall and currently weigh 68kg at about 20% bodyfat. I had severe asthma in my youth and couldn't do any physical exercise, and even when my asthma lessened I just never got into it. So basically I'm starting out from absolute scratch. I've picked up a zero-to-hero running scheme a few weeks ago and am following the program, running 3x a week, which is going well. I can run for an 8 minute stretch now, while the first week in I was almost dead after 2. But running won't help me convert that fat to muscle, which is where simplefit comes in.
I've been trying out the bodyweight exercises, but it's still very early for me. I had to sub jump-ups and even the push-ups are of the 'girly' variety. Still, I managed to do my first chin-up ever this week and you wouldn't believe how huge the grin on my face was

My questions:
- I run monday, wednesday and friday and I'd want to do the SF workout on the other days, i.e. tuesday, thursday and saturday/sunday. Is it okay to combine them this way? The running scheme says that as a beginner I really need to rest my body on the off days, is the SF workout different enough from running that it still counts as a rest day? And does the running not interfere with SF? Or should I really keep my rest days and do the running and the SF workout on the same day? I don't want to overstress my n00b body and injure myself early in the game.
- On the D1 workout, what should I do if I can't do another chin-up but I think I still have some push-ups/squats left in me? i.e. does the workout end when I can't do 1 part of the round, or if I can't do any part of the round? If I can't do a proper chin-up anymore after a few rounds, should I substitute a jump-up? Or stick to substitutes altogether until I can do enough chin-ups to fill the 20m with rounds?
Thanks for your help!