GLASS BLOCK INSTALLATION MORTAR 

Good question Me Mate. You can put a silicone bead around the perimeter once the mortar is dry and set, however at the base of the frame which acts as a sill tray you would have weep holes for drainage.

absolutely 3 parts sand 1 part cement. Always good to add a damp proof additive in the mortar for external walls

Make sure that you allow for oral to be squeezed into tha sides and top and bottom

you can however we wouldn't recommend do this as you will get condensation and mold appearing within side the block.