Bernard - How to increase friendship:
1) Helping him out ( stops working after some time).
2) Refusing money when Bernard offers it after sickness quest is finished.
3) Going with him to the hut in the forest (only during Friday night) (Available after Lost Friend quest is completed, also gives you 1 heart with Bernard).
4) Bar meeting - only after like 25+. Bernard asks you to go to the tavern with him (available after sickness quest)
5) Offer your services for the day - Before 12:00, requires at least 1 heart with Bernard.
6) Hot spring scene - requires at least 1 heart. Available on Sunday/Saturday after 18:00.
Caleb - How to unlock him:
You unlock Caleb after doing the whole ''Full Moon'' questline, a whole rundown of this questline is written inside the Event log. (I recommend doing ''The Cruse of Lust'' before ''Full Moon'', as you will need access to the night witch)
The Night Witch can be found in the Witch's hut in the Swamp area, while looking through the Dark Swamp. (Dark Swamp is unlocked by doing the Lost Acolyte quest from Othra.)