1.
find / -name "*.exe" -executable -size +1k
or
find / -regex ".*\.exe" -executable -size +1k

2.
find / -name "*.c" -size +100c
or
find / -regex ".*\.c" -size +100c

3.
find / -type f -regextype posix-extended -regex "(.*A.*a.*)|(.*a.*A.*)" -exec tail -n 3 '{}' \;
or
find / -type f -regextype posix-extended -regex "(.*A.*a.*\..*)|(.*a.*A.*\..*)" -exec tail -n 3 '{}' \;
or
find / -type f \( -name "*A*a*" -or -name "*a*A*" \) -exec tail -n 3 '{}' \;

4.
Name without extension
find / -mindepth 3 -maxdepth 5 -user scanzio -size +249c -name "????" -type f -exec wc -c '{}' \;
Name without extension with regular expression (remember that the path must be matched)
find / -mindepth 3 -maxdepth 5 -user scanzio -size +249c -regex ".*\/...." -type f -exec wc -c '{}' \;
Name with any extension
find / -mindepth 3 -maxdepth 5 -user scanzio -size +249c -name "????.*" -type f -exec wc -c '{}' \;

5.
find / -name "A*zzz*.???" -exec tar -zcvf '{}'.tar.gz '{}' \;
or
find / -regex ".*A.*zzz.*\...." -exec tar -zcvf '{}'.tar.gz '{}' \;

6.
find / -type d -name "bin" -exec ls '{}' \;

7.*
find / -name "*.c" ! -user scanzio
or (but only if fields are separated by single spaces, and not multiple spaces)
find / -name "*.c" -exec ls -la \{} \; | cut -d " " -f 3,10 | grep -v scanzio| cut -d " " -f 2

8.
find / -maxdepth 1 -user scanzio -exec chmod go-xrw '{}' \;