This list looks very solid.
-When you cast a Cure spell, you may immediately make a Heal check on the target, providing their effects while skipping the time for normal treatment.
--You must choose the check's desired effect and strength before the roll.
--The chosen/rolled Heal result is immediately applied.
--The Heal check results you can apply with a spell is limited by the spell's level. Perhaps link this to the Heal DC, with higher level spells allowing a wider range of DCs
Presumably CCW allows you to try for up to 80%, CSW up to 60%, CMW up to 40%, and CLW up to 20%.
Unless we want to integrate
Heal, which is currently getting the short end of the stick.
--You can determine the state of the subject's health and conditions affecting the subject with a diagnosis, with higher DCs for less obvious effect types, greater detail or taking less time. Default is say...10 minutes. This has no chance of harming the patient, and can reveal the DCs for treating the chosen conditions.
Use a -10 penalty for rushing (taking one minute instead of 10), and a further -10 for reducing to 1 round, perhaps?
The base DC should probably derive directly from the save DC for the effect where possible.
--You must declare the desired Heal effect and DC before rolling. In the case of effects with variable DCs(such as curing poison), if your chosen DC is below the required DC, the treatment does nothing and does not harm the patient.
--Failure to meet the chosen check DC damages the patient, depending on how far you failed the check by. Damage is as per percentile healing.
This is an interesting change; currently attempting to cure poison or disease (by substituting for the save) has no penalties except a long treatment time, and failure does nothing special.
--You can remove permanent conditions such as paralysis, blindness, curses, etc, with a DC of X+their save DC, where X depends on the condition. This takes several hours. Effects with multiple saves(like disease, poison and some curses) require a successful check for each save attempt.
I suggest building a table on a hidden formula for X, something like (level of spell that can cause effect) * 5, and supplying the minimum expected save DC for each, also based on the lowest-level spell that could cause it.
Fake edit: Oh look, snakeman already did this!
When casting a Conjuration (healing) spell, you may make a Heal check as part of casting the spell. If you succeed on a DC15 check, you heal the target for an additional 5% of their maximum hit points. For every 5 points by which you beat the DC, you increase this bonus healing by another 5% of the target's maximum hit points (to a maximum of 70% bonus healing at DC 80). You may also voluntarily raise the DC to remove certain conditions. Exactly which conditions can be removed depends on the level of the healing spell you are casting (requirements given are minimums, not maximums). Regardless, the Heal skill cannot remove more conditions than the spell level when used in this way. On spells that have multiple targets, these extra benefits are only chosen once and apply to all targets. Spells with non-instantaneous durations only apply these extra benefits once at the beginning of the spell.
Remove Poison: Increase DC by poison DC-10, requires 3rd level spell.
Remove Disease: Increase DC by disease DC-10, requires 3rd level spell.
Remove Paralysis: Increase DC by 10, requires 2nd level spell.
Remove Blindness: Increase DC by 10, requires 3nd level spell.
Remove Deafness: Increase DC by 10, requires 3nd level spell.
Remove Sleep: Increase DC by 5, requires 1st level spell.
Remove Fatigue: Increase DC by 5, requires 1st level spell.
Remove Exhaustion: Increase DC by 15, requires 3rd level spell. May be reduced to Fatigue with a DC10 Heal check requiring a 1st level spell. If this is done, the Fatigue cannot be cured in the same spell via the Heal skill.
Remove Sickened: Increase DC by 5, requires 1st level spell.
Remove Nauseated: Increase DC by 15, requires 3rd level spell.
Remove Dazzled: Do not increase DC, requires 0th level spell.
Remove Daze: Increase DC by 15, requires 4th level spell.
Remove Stun: Increase DC by 20, requires 4th level spell.
Also, when casting any Inflict Wounds or Harm spell, you may make a Heal check, causing the target to receive extra damage equal to the extra healing on (Healing) spells for their result (including the same cap). This additional damage is calculated before the saving throw.
This still needs a limit on percentage healing for CLW etc, at the least. Otherwise, it's a good minimal change.
Although, it requires spells for all of these, rather than allowing mundane solutions at higher DCs. I think an alternate solution for each of these (for the most part) should be allowed with a sufficiently high Heal check.
--You can remove temporary effects like spells or short term conditions on living creatures with a full action. The DC is based on their save DC+effective spell level.
Including, I suspect, a caster level check of some sort, like
break enchantment?
--You can return the freshly dead to life with a high DC check, but unless you also repair whatever caused their death in the same check(see below, e.g. combining healing with this), the person dies again.
If this is supposed to substitute for
raise dead directly, which I think would be in poor taste, the DC would be around 40 or so; if it's supposed to supplement it at higher levels, which would probably work better, shoving it to 50 or 60 might be fine.
--You can combine multiple of the above into a single roll, but this stacks their DCs and takes the least favorable of their individual time requirements, as well as combining the effects of failure for all.
Specifically, DC A + DC B - 10 + DC C -10. Similar effects (e.g. curing multiple diseases) may gain an additional +5 bonus for each added effect (beginning with the second).