Hello and welcome to the forum.
Without going into too much detail, the training plan you’ve stumbled upon is both sensible and measured, in that it encourages progressive overload of the muscle fibres from the outset, something that’ll allow you to increase size and mass rather quickly in the first few weeks.
However, provided you warm the muscles sufficiently before-hand (the rowing machine is a great choice), in the initial interim, I think that you could drop the easy sets and execute sets using the same amount of weight, one that represents 60-70% of your 1 rep max, in order to accustom your muscles.
As the strength of muscle fibres increase through progressive overload (adding additional weight to the bar), after around a month of lifting weights, I don’t see why you couldn’t progress to lifting 70-80% of your 1 rep max.
Moreover, since the vast majority of the suggested exercises are compound movements, (utilising more than one muscle group), they’ll serve to allow weight to be increased rather quickly, whilst priming muscles to be worked in isolation. If you notice, the last three scheduled exercises are all isolation movements.
As for the frequency of your intended schedule, as a beginner, I’d say that resistance training three times a week is more than sufficient, since the muscles will require 24-48 hours recovery in between. If you wish to incorporate additional training, I’d suggest introducing cardio intervals into your schedule, eventually progressing towards HIIT.
Following a warm up, cardio intervals should last no longer than 30 minutes and HIIT no longer than 20 minutes.
Diet will also play an important part in your desire to improve body composition. Consequently, I’d advise not to introduce a deficit through calorie intake, allowing the calories expended through exercise to create the deficit, instead.
As such, I’d recommend that you consult BMR/TDEE calculators, to gain a clearer understanding of how many calories your body requires on a daily basis, paying particular attention to your TDEE (total daily energy expenditure).
Given that current your goal centres around increasing mass/reducing body fat, you don’t want to restrict calorie intake. Having obtained your TDEE, aim to consume the recommended daily amount, as the body will utilise excess energy (stored in fat), to ensure that sufficient calories are received to support your level of activity.
Additionally, by consuming around 1g of protein per lb of body weight, you’ll ensure that the body utilises fat, and not existing muscle mass, to provide the energy needed to support your intended level of endeavour.
You may consider an excess of 8KG to be huge, but in the grand scheme, it isn’t. Since you intend to begin lifting weights, the excess you possess will quickly begin to diminish.
