Oooh, I'll bet you're counting the hours now! I think you're okay with another FVRCP after two weeks but I wouldn't repeat a fecal now since he was just treated. Bring in the health records with you so that your vet can have a copy for his chart.
As for the wormer, I'm not sure I quite understand their schedule. I usually give a dewormer then repeat in two weeks - I try to follow this routine twice a year, although once a year might be okay if you are not ever feeding raw.
It is true that different water sources have different levels of bacteria and other parasites, especially giardia, but I don't know that using bottled water transiently is going to protect him from ultimate exposure if you switch back to tap.
When your boyfriend picks Loki up it would be best to just pop him in the car and bring him home. He should play it by ear whether to give him space initially or try to interact with him right away. If Loki pops out of the crate looking for loves and giving headbutts I would give him the attention he is seeking. If he appears shy and hesitant I would leave him alone for a bit and let him do some exploring on his own before imposing yourselves on him.
Be sure there is food, water, and litter easily accessible. He may not use any of them right away but it will be helpful for him to know where they are when he is ready. I would also leave the crate in the room for at least a few days since this is his safe haven with smells and items from his previous life.
And of course we will all be waiting impatiently to glimpse the first pictures of your precious little boy once he arrives!!