No to the first question. An IDE channel has 2 devices, master and slave. SATA is a "home run" without that so there is no such setting and what you do on the IDE channel is up to you but I would never set it to slave alone on the IDE channel.
1. YOU determine this. Certainly it's not a hardware or OS issue.
2. Again, this is mostly determined by you and your skills.
3. It means exactly that and is a FALSE or phantom security. It does not mean you can avoid backup because you are installing the OS to your other drives. Folk seem to latch onto the data only drive idea and it appears must learn the lesson first hand. If you don't backup, your choice.
4. YOUR CHOICE again.
These are not dumb questions but most are answered by your choices.
I have 2 Sata drives in my PC and i'd like to connect anther IDE drive, should I do something before connecting besides configure it to 'slave'?
Can I use 2 different SATA's for 2 opperating systems?
will it work as a dual boot or should I install 2 OS on 1 Sata.
And what does it mean to use a drive for data only?
does it mean anything besides an OS?
And sorry if my questions are too dumb im new to this.