With reference to backup type (System Backup/Database and Media Backup/Database Backup):
What do you consider is good practice (type and frequency)?
I think, if you have previously faced the consequences of not creating a back-up and therefore, after that, have defined a specific back-up cycle, which you follow religiously, then I would consider going with either of this type - "Database and Media Backup" or "Database Backup".
More specifically, going with the "Database Backup" backup type is the most recommendable option.
If the scenario is different wherein you have never ever come across any difficulties while running the store and therefore, have never given a thought about backing up your system and then, I would strongly consider the first type, which is "System Backup" and after that, establish a convenient back-up cycle with an approach to imitate it strictly.
Hope it helps!
It also has to do with how often your host is backing up these materials for you, and how long they're holding on to them. You may not want to waste resources on holding on to as many local backups if your host is properly maintaining offsite backups.