It looks like Steve Winter has weighed in here that what happens is that the values stack, meaning :

• With no rest (fighting, casting) : 0HP/day
• With rest (traveling allowed) but no help from a healer : 1HP/day
• With rest (traveling allowed) and help from a healer : 2HP/day
• With bed rest (no traveling) but no help from a healer : 3HP/day
• With bed rest (no traveling) and help from a healer : 5HP/day
• With bed rest (no traveling) and help from someone that is both a healer and an herbalist : 6HP/day

Mostly Yes

The skill Heal has several uses, many of which are usable on oneself.

• First aid to stabilize a dying creature. Success stabilizes the creature. This is extremely difficult to use on oneself. The feat Diehard is of no use (if the creature with the feat chooses unconsciousness it stabilizes, and if it chooses consciousness it's not dying, instead losing 1 hp when it takes a standard or strenuous action). A generous reading the feat Ferocious Resolve allows a dying creature to use first aid on himself the round after damage is inflicted that reduces him to negative hp if the DM determines this is, according to the feat, "fighting" (fighting for his life, maybe?); success means the creature stabilizes this round and is unconscious the next.

  A dying character becomes conscious but not stabilized--an exception to the dying condition--if exposed to smelling salts; combined with the feat Deny the Reaper, which allows first aid checks to be made as move actions, a character can stabilize himself without falling back into unconsciousness if the DM determines such an act isn't strenuous. This is an overpriced and very niche trick for a character possessing an animal companion or familiar; teach the creature to pour potions of cure light wounds down dying creatures' gullets instead.

• First aid to end the condition bleed. While the Heal skill specifies first aid only stops hp loss from the bleed condition, the bleed condition itself is unclear if that's the case. Either way the DM rules, a creature can use first on himself to end the bleed condition at least if the bleed condition's inflicting hp damage.

• Long-term care. This straight-up says, "You cannot give long-term care to yourself." As with nearly everything in Pathfinder, there's an exception. An oracle with the life mystery can choose the revelation healing hands, which, in addition to other effects, says, "You may provide long term care for yourself."

• Treat wounds from caltrops. A creature can use the Heal skill to treat his own caltrops wound.

• Treat wounds from the spell spike growth or the spell spike stones. Yes, only those two spells, and, no, the creature can't treat the wounds himself: "Another character can remove this penalty by taking 10 minutes to dress the victim’s injuries and succeeding on a Heal check against the spell’s save DC." Emphasis mine.

• Treat deadly wounds, treat poison, and treat disease. A creature can perform these skill uses on himself. Note that the treat deadly wounds skill use requires the creature to list injuries separately and calendar the injuries ("A creature can only benefit from [treat deadly wounds] within 24 hours of being injured and never more than once per day"). As this is an excessive amount of bookkeeping given the game's combat-heavy nature, I urge the DM to house rule that a character can instead only receive the benefits of treat deadly wounds once per 24 hours.