I've definitely learned a lot since this was my first game dming dnd (lots of prior experience dming other games, and playing dnd)... anyways, i'm going to make the prestige classes since i've already balanced my current campaign for having them, but i really don't like the idea and would ideally convert to a system similar to your cleric domains where each class has one or more new FFH class options that are balanced (i know asking alot)
one thing i have been rethinking is the races...
FFH has: humans, orcs, dwarves (mountain and hill) elves (svartalfar, ljosalfar, and the not elves), centaurs, lamias, knolls/musteval, satyrs, and lizardmen(not to mention what i see as nonplayable races like frostlings, elementals, angels and demons... as well as the extinct aifons)
DnD has: dwarf (mountain and hill), elf (wood, dark, and high), human, halfling (lightfoot, and stout), dragonborn, gnome (forest, rock, and deep) half elf, half orc, tiefling (and aasimar with dmg)... not to mention elemental evil race: aarakocra, goliath, genasi (earth, water, wind, fire)
so the question is... how do you reconcile the races?
just brainstorming here, but here are my ideas: (dnd race on left matching to ffh race)
Dwarf: there are mountain and hill dwarves in both dnd and FFh (no problem here.. although giving hill dwarves rock gnome racial stats makes sense to me as well [without the small size of course]
Elf: Since there are three types of elves in both ffh and dnd, i am tempted to say wood=ljosalfar, dark=svartalfar, and high=not elves (rare tho they may be)...problem is the svartalfar and ljosalfar are both the same race, and tho the not elves may have been changed they are extremely rare, and probably not even technically elven by dnd standards. (so for now i am taking the easy way out)
Human: same everywhere... duh, no change here... (although i feel like using the optional feat rules and choosing certain feats and skills for the members of different nations, but that's just getting into nitpicking and the players are free to choose as they wish)
Halfling: this is a hard one... in my game i just said that they exist everywhere humans exist and have never been able to create their own unique culture or empire... but... we may be able (with some good old fashioned reskinning) be able to integrate them into the ffh world without breaking lore. the Mustevans are the mouse/dog people the kuriotates use as their recon units, i imagine it would only take a minimal amount of tweeking to change the halfling to the mustevan.
Dragonborn: seems easy enough... they are lizardmen, problem for me is that dragonborn can breath fire, and the lizardmen can't so either they are some form of advanced lizardmen or you remove their only advantage as a race.... again , i'll take the easy way out and break lore a bit to accomodate them, but i have also been playing around with the idea of saying that their stats fit lamias (who are commonly kuriotate casters)
Gnome: SUPER TRICKY... in my game i said that gnomes were the elven version of halflings, but since we are trying to keep things lore friendly, we run into some reskinning issues. My 1st idea is to reskin forest gnomes as satyrs (beast speach and illusion seem to fit them well enough) rock gnomes may replace hill dwarves... or possibly just be another caste of dwarven society... deep gnomes have no place in the lore as i see it... maybe they are chosen of kilmorph cuz stone camoflauge and enhanced darkvision, but that makes little sense to me, and i would probably just omit all the elemental evil races.
Half elf, and half orc: simply a mix of the human and orc/elven races... no reason they can't exist, although maybe give the half orc some kind of fire resist (as long as its balanced)
Tiefling and Aasimer: if humans can have babies with orcs and elves, they can do it with angels and demons... as long as hyborem and basium are in the game, these races can exist just fine.
missing races: FFH- orcs, centaurs, lamia (maybe) dnd- all elemental evil races
Playable orcs is a tricky issue, and there may be some way to reconcile goliath with ffh orc, but it would require a bit more work and would be hardly recognizable as a goliath anymore, lamia could be a reskined dragonborn, or perhaps one or more of the genasi... centaur.... um... probably will remain a nonpayable/monster race.