| | Re: going and coming back to a place - i'll be back from place?
First your sentences ...
1. Don't use to together with home - just I'm going home ...
2. a)Leave for is correct in general but sounds odd for a short trip. It's usually used for a longer journey. So : if I was on holiday I might well say We're leaving for home tomorrow, but not if I was just at the office or something.
b) return is a bit formal for this context. be back or come back would be more normal.
c) Because you've started I'm leaving ... you either need to go on with the same verb form after and or include will. So either I'm going home and coming back in an hour or I'm going home and I'll be back in an hour. The rule is that after a co-ordinator (and, but, or) you can only omit elements if they were exactly the same in the previous clause.
3. This is fine, other than the over-formal return again. But of course the meaning is different from (2). The use of Be +Ving suggests this is something you'd already decided - you're just informing the listener. Will suggests a spontaneous decision. So :
- Can I see you for five minutes?
- Sorry - I'm going home now. But I'm coming back in an hour.
- Is John here?
- No, he's out till two.
- Oh - well, in that case I'll go home and I'll come back in an hour.
In British English it's common to use I'm off, instead of I'm going. So :
- I'm off home now, but I'll be back in an hour (the will here expresses a prediction rather than a decision)