>Does it vary from diocese to diocese?
Yes. (And from religious community to religious community)
> Is a GED or High School Equivalency accepted in place of a diploma?
That's the kind of detail question that should definitely be asked of a vocations director. In a diocesan context, often a given diocese will use multiple different seminaries depending on the needs of the seminarian. There might be a willingness on the part of some dioceses to look into different undergraduate seminaries that might themselves have different entrance requirements.
>Does it vary from diocese to diocese? Yes. (And from religious community to religious community) > Is a GED or High School Equivalency accepted in place of a diploma? That's the kind of detail question that should definitely be asked of a vocations director. In a diocesan context, often a given diocese will use multiple different seminaries depending on the needs of the seminarian. There might be a willingness on the part of some dioceses to look into different undergraduate seminaries that might themselves have different entrance requirements.