Alot of the people who worked on the channel 7 version are also returning to the new channel 10 version.Leon Murray is already basically confirmed as the main voice. Peter's voice was used in the first teaser, yes. I'm not sure if that was recorded specifically for the promo or was just taken or modified from an early series. We'll likely get a couple different voices (hopefully). Rumour has it a large portion of the production team is from the original 10 era, so it's not impossible but I don't think likely. Wouldn't expect many cameos, if any, in that respect to be honest. We're more likely to see ex-housemates make some sort of appearance.
Regarding the voices, I would've preferred the Nick/Rikkie (5-7) voice team over Leon, but I liked Leon's enough to not be fussed. Maybe we'll be surprised! Given we're less than a month away I'd have thought we'd hear of who's at least producing it at this point. If it's an original producer we'll likely be able to guess on some aspects of the show.
While that concerned me initially my friend who is working on the new series and worked on the channel 7 series said everyone hated the channel 7 version and are over the moon to be doing big brother the correct way. Unfortunately couldn't get any insider info as they are sworn to secrecy