Oh, and Torchwood season 4 starts filming in February according to folks on location at the DW filming. RTD has as much as said any future series will be called Torchwood: Story title as in Torchwood: Children Of Earth. It's unlikely to be about Torchwood 3 guarding the rift - they're just Torchwood now - as he says it's an umbrella for telling good SF drama. (http://io9.com/5324964/we-asked-russell-t-davies-our-most-pressing-doctor-who-question)
Despite RTD saying probably 5 episode seasons, Barrowman thinks it'll be 13 in this interview:
http://www.channelguidemagblog.com/...-of-earth”-kills-capt-jack-over-and-over-and/
RTD said:the show had "found its tone," so future outings would definitely be one continuous story - possibly five episodes, possibly longer. But definitely, there'll be no return to "monster of the week" type stories. He liked the way the miniseries had "Torchwood" followed by the subtitle "Children Of Earth," making it part of the show's title. So that'll probably happen again next time.
Added Davies: "Torchwood has become an umbrella for telling a good story. This wasn't anything to do with Cardiff, or the rift," or any other standard elements of the show.
If the show does come back, "everyone who survived" will return as well. But the show will also do what "Children Of Earth" did with John Frobisher and the other new supporting cast — introduce a whole new set of characters. Davies doesn't believe in replacing a character after he/she is killed off, because it seems heartless, like buying a new puppy right after your dog dies. That's why, in "Children Of Earth," he deliberately introduced a "replacement" for Owen — and then shot him.
Despite RTD saying probably 5 episode seasons, Barrowman thinks it'll be 13 in this interview:
http://www.channelguidemagblog.com/...-of-earth”-kills-capt-jack-over-and-over-and/