I'm trying to reseal a three piece acrylic/fiberglass shower surround with a prebuilt acrylic shower pan. The old silicon sealant was starting to mold and mildew pretty badly and was leaking around the right bottom edge of the door destroying the baseboards adjoining the shower. I have two questions regarding how to seal this:

1) Do I seal the seam between the door and the shower on both the interior and exterior of the shower?

2) The previous owner had filled the weep holes at the seam between the bottom of the surround and the start of the shower pan with silicon sealant. From my research, these are meant to allow water to drain which gets behind tiled shower surrounds since tile and grout are not water proof. Is it necessary to leave these open for three piece showers as well? I would think that the acrylic itself would be waterproof. Is it customary to install a waterproof barrier behind the acrylic? If not (or if the previous owners had skipped that step), I would assume that leaving the weep hole unsealed would cause water penetration to the walls?

TIA for the help.