Вы не ждали нас, а мы припёрлися.
“for there whole life” — здесь there бессмысленно, а ты почему-то не стал менять.
“abilities and skills acquired” — “interests and skills developed” [как вариант]
“The official admission is going at the August 15 to September 15, but it is possible to be admitted during the whole school year.” —
“An official enrolment in classes takes place every year from August 15 to September 15. If there is a shortage of pupils, new ones can be enrolled during the school year.”
”, we organize the city tourists competitions of pupils during 27 years up to year 2011.
“; from 1986 to 2011 we conducted municipal tourist competitions for schoolchildren.”