Could I leave an iPhone 4 charging for a week?

First question, will imessage/facetime work on a mac over just Wi-Fi internationally? I'm going on vacation and decided not to take my iPhone but think I will leave it charge so all my notifications are up for me as when I've gone away before I've lost some info. Are there any negatives to leaving it charge for a week? Any better alternatives?

Continuously charging will reduce the quality of your battery faster its better to unplug it when you reach 100% and drain it to ~10% before plugging it back in. If you are not going to be there, I would recommend shutting it down and putting it in a drawer.

Bad idea.

No I don't think you should, because once it reached 100% there's no need to keep it in longer, because your going to waste Energy! & your IPhone is going to be sizzling pipping hot & it takes a while to cool down so if you wanna Burn your hands & waste energy, Go ahead but you shouldnt.

Your iMessage and Facetime will still work, of course but you shouldn't leave your phone charged for a week because it will lessen the life span of your phone's battery. You could just leave your phone alone and it will still get notifications so there's no need to leave it charging because it wouldn't run out of battery while no one is using it.

Yes FaceTime and messages will work. If you overcharge your phone, it can malfunction.