So please feel free to answer as many or as few as you can

The basics are that, after decades of hit and miss attempts to regain the fitness of my youth, I was a good runner, did full contact kick boxing, etc, I've now, more than 20 years after my accident, actually got myself to th stage where I can have a "routine" because my sin has joined the local karate class and needs to fix up himself as to being able to do press ups and kicks and stances and all that stuff.

So now the questions,

I've only been doing press ups and (with my newly purchased 5kg dumbbells) shoulder presses, mainly because my shoulder joints are fucked and I want to at least make them stronger. But after only a week of 30 minutes an evening, 5 sets of 10 press ups and the same for the shoulder press, my shirts now feel really tight around the shoulder area.

They are my work shirts and at first I thought it was because I was wearing a tanker underneath, but even without one they are notice my tighter.

Should it have made such a notice or difference after only 8 days of light excercise? It's deffo easier to do the movements now but I wasn't expecting such quick resluts, so is this normal?

Secondly, I'm eating more, not more as in eating bigger portions, I'm feeling hungrier more often than before, is this simply due to the exercise?

And if so, what should I be eating more of to keep the hunger at bay?

I'm nit into all this protien shakes and stuff if I cam help it, can't I just ear an extra banana or potato or something? Don't want to go all health freak and have a heart attack or the like

And lastly, junior is 5 so I'm thinking it's a little bit young for him to be hitting the weights and have had him just doing press ups and square and sit ups and stuff ratherthan curling and squaring with big lumps of metal, yes or no to this approach?

Cheers for any helpful hints, I can't help wondering why I didn't do this before