It would depend IMO. It should be very rare that a 3 loss team gets in but it could be possible depending on how a season plays out and who they lost to, (say USC was really good this year but lost 27-23 type games to #1 Oregon, #2 Ohio St, and #6 ND while killing everyone else on the schedule). Technically it could be possible to still have that team in the top 12 so I’m not big on absolutes like the 3 loss rule.
There are a few issues with the playoff that need to be addressed. The provision of conference champs getting a bye also needs to be looked at. Why is Boise St (as of now) getting a top 4 seed and a bye week while Ohio St gets seeded lower with a first round game? I think the seeding should be based on the committee like March Madness.
There shouldn’t be a reserved spot for the G5. If they have a team good enough and ranked in the top 12 like Boise this year then they should be in. However, we shouldn’t be saving a spot for a #24 ranked team to jump multiple more deserving teams simply because they’re G5 and get special privileges.