to lose 3ish kg of fat *only*. Suggestions? Slow and steady?
1. Beginner: Absolutely no junk calories.
2. Intermediate: Go on a diet. In addition to no junk calories, remove the pasta, white bread/rice, breads and especially CAKES! Less calories.
3. Advanced: Oh, so you are serious about this? Try the zone diet (30/30/40 protein/fat/carbs). Best diet for a strength athlete looking to get lean and keep muscle. Yes, you will really have to cut down on carbs and get more healthy fats in your diet. Get ready for 1.0+ grams protein per lb body weight. Enjoy your sexy new body.
1. Beginner: Walk/bike more often. Get some regular cardio sessions in.
2. Intermediate: Metcons or Sprints. For metcons, at the end of your strength workout try something like 7 clean (with squat) & press followed by 10 jump squats (no weight) followed by 5-10 pull ups. Repeat for 5 rounds. Very minimal breaks. For sprints, try running hill sprints or sprint intervals on a bike trainer. Very hard intervals of 15-30 seconds in length followed by 2-3 minutes of rest. 8 intervals or so should do.
3. Advanced: Why not metcons, sprints AND light spinning sessions? You could do the metcons & sprints 3 x week on the same day and do the light spinning/jogging/walking sessions 3 other days per week. YOU'RE AN ANIMAL!!!
Provided overall caloric intake is managed and there is a deficit, there is no reason to remove the foods you listed: junk food, cakes, white/bread pasta from a diet.
As long as you hit sufficient protein and fats, and the majority of your food is healthy, these 'taboo' foods are totally fine - and in the interest of staying sane / not having your diet control your life - should be recommended.
The rest of your advice is sound, but I felt compelled to call you out on that point.