Present perfect use in practice

Hi. Please help me with these present perfect uses and some side questions on example sentences

1. Let us pretend someone writing/telling something about his friend. Are these sentences (including those last two setences with present perfect) correct?

1. He was born in a country town of about 50,000 people.

2. He attended his elementary, middle and high school in the same town. (I think having the word "school" in singular is correct since he attended one elementary, middle and high school. - Am I correct?)

3. He has been to Ireland many times in the past.

4. He has made many friends in his current school since coming there in 19XX.

2. Let us also pretend someone is applying for a sales person position. Do you think the sentences in present perfect in the "side note" section/part are correct (or perhaps - good writing)?

1. He has extensive experience is sales, including XX years at a car dealership, achieving top sales figures four different sales periods during his employment. (Do you think having a participle clause starting with the word "achieving" modifying another participle clause that starts with the word "including" is correct (or possibly - good writing)?

2. On side notes, he has travelled many countries all over the world to broaden his world view and attain global perspective, and has just completed a management program at a local university, while working full-time at the present company.