cron prefix/restrictions
 

Hi, will be possible to add some prefix or some another restriction to user cron commands, that they will only be allowed to insert URL there or only run commands like /usr/bin/wget -O http://www.somedomain.com/cron.php ?

No, this is not possible

Is it also impossible to add command path restriction that users will only be able to run as a cron job command from specified path like for example "/usr/local/ispmgr/bin"? I don´t want to allow users to run all system commands ...

Used the system crontab which does not have these limits and restrictions