Aero K questions

Hello!

I am taking a flight from Osaka to Seoul through aero k airlines and I have a few questions.( booked a basic ticket)

I’ve tried looking this up and I’m getting mixed/unclear answers

1)is a school backpack allowed to be a personal item? I do not own a purse and wanted to use my backpack as a personal item

2. are they super strict on sizing for carry ons? I have a small suitcase that I would like to see if I could use as a carry on but I think it’s too long and wide (like 2-4cm over the limit)

3. what was your experience like? I’ve only flown delta and this was the only airline that fit my time schedule requirements

4. are they strict on weight? I’m 1kg over the weight limit (15 kg for check in, and 10 for carry ons)

Thank you so much!!