for the bathroom click on the keyhole.
for the shower go outside and click on the top of the tree.
for the water game you try to sabotage the girl by throwing your own water bottle at her glass and drink some yourself by 1) right clicking the bottle. 2) left click to activate target mode, during which you can hover your cursor on top of the girl's glass and then right click to throw or you could 3) hold the left mouse button to pour water on your own glass then let go of the bottle by letting go of the left mouse button and 4) hold left click when hovering on your glass to drink the water and just repeat.
the store sells game stuff like more water for the water game and an ability for the bush and bathroom event to see the whole screen.
which meter are you referring to?