Concerning the 12-month period, that is left to the member's discretion. There is no obligation to take 12 months of leave. A member can make a judgment call and decide to be present for two months because an important issue for them is under consideration, and then decide to take a month to be with their child.
The parliamentary calendar is often made up of three-week blocks of sitting, after which members can return to their riding for a week. The member could elect not to return to the House during the week in the middle of that block, to avoid having to make a round trip over the weekend. In general, members make a round trip in less than 48 hours, to make the trip less difficult. So a member could choose to spend the middle week in their riding, to avoid round trips over a weekend. That would be possible to do over a 12-month period.