1. You should still do that. The incremental backups only record the files which were added or modified since the last backup. If you have 90 days of incremental backups you end up having to restore 90 backups to get your site to working order which is, uh, let's say far from ideal. Having a weekly full site backup means that at most 7 backups (weekly + 6 next days' incremental backups) would need to be restored.
2. Create as many profiles as you want. Then create a scheduled backup for each backup profile with different scheduling settings. For example, I'd do a full site backup on Sundays and an incremental backup on Monday to Saturday (but not Sunday, since we have the full site backup).
Note: you should do a "Full site (incremental files)" backup on weekdays and Saturdays. Otherwise you wouldn't have a copy of the database which is problematic on its own right.
Nicholas K. Dionysopoulos
Lead Developer and Director
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