1 year for all four is definitely possible, I think 4 months for 1000 pages is good.
250 pages/month is only like 20 pages/day.
As for the translation, I don't think that's super important on a first read. Having people join who have read other translations could give some insight, but I think those arguments are more for the scholars who read them all the time and want to argue about specific phrasing on a page and not the overall meaning of the text.
Also still kinda interested in running a Borchardt "People's Marx" reading group in parallel for anyone who drops out of the main group. So they have a 300 page fallback that gives them context that might help them get back into capital.