Kind Wayfarer + Forbidden Fist sounds like a good synergy because of the healing from White Flames and Lay on Hands and Exalted Endurance that can support your health while under the curse. And Eternal Devotion's lash will stack with Turning Wheel's, too. Slap on the Ring of Focused Flame and your White Flames will have great accuracy, too. Pick Scion of Flame and the PEN will be great, too.
Only thing that feels not so nice to me is that White Flames (the KW's Flames of Devotion) is best with dual wielding because the healing procs twice then. This is a huge advantage imo. Forbidden Fist attck is not a full attack so shield setups make a lot of sense. BUT: once you pick up Tuotilo's Palm you'll have the best of both: weapon & shield AND dual wielding AND great enchantments for the Monk's side of the build.
On top of that - since Forbidden Fist profits so much from maxed RES - they also fit very nicely thematically. Paladins with high RES make a lot of sense, too.
All in all you can become very, very tanky while also having great offensive capabilities. And let's not forget that White Flames also heals your allies in range (and that range is increased by +10 INT from the Monk's side of course). Just don't pick the resistance passives of the Paladin!
Sacred Immolation's self damage is a separate effect from the offensive part - its duration gets shortened by high RES and stuff like Clarity of Agony. So using Sacred Immolation (which is a great damage boost) isn't as risky as it usually is with "normal" paladins. Paladin/Monk is like it's made for Sacred Immolation (or the other way round). The self damage will wear off pretty quickly and even grant you a wound when it's ending. The burning part will still carry on. Like with the curse though the hostile part will get prolonged with higher INT.
I think all in all it's a great combo - it's not very "gishy" though?
---
Street Fighter (I'll get to your question below) has an enormous potential for weapon damage. And with the Forbidden Fist it's quite easy to lower your health to 50% willingly in order to trigger the Streetfighter's passive without getting flanked. Combine with Human to also profit from Fighting Spirit at 50% health. But since operating at 50% health is risky one might - in this case - use Iron Wheel and a lot of CON + Tough and maybe even an Amulet of Greater Health in order to make the 50% of health still be a lot of health. Streetfighters don't profit a ton from high INT as they usually don't use a lot of AoE or duration-based stuff (except maybe Toxic Strike) - and while the loss of a multiplicative burning lash in combination with such high damage bonuses does hurt your dps, I think the convenience of a much bigger health pool and thus the more reliable approach to "keep me under 50% health for massive dps gains" is just better. Getting knocked out all the time is no fun after all.
I made the same experience with a Helwalker/Berserker: very potent but dropping dead all the time. As soon as I rampoed up the health pool to the max it became much more enjoyable and performed actually way better even though on paper it had less dps potential. But it's only potential. What is that worth if you cannot make it happen?
Using a pet that does high "heal on kill" makes a lot of sense here. If you have Eder you can make sure he picks one that does a weaker version of that effect for the party, too. You will kill quickly so you will heal a lot, too, giving you access to even more "risk free" FF attacks.
By the way: Trickster/FF is an even better combo overall imo because you can lean into the defensive side more, become very tanky and still have great damage output. Also seems to be more on the gish side with the spells the Trickster gets.
---
What about FF/Berserker? You can shorten the duration of the confusing part of Frenzy a lot so that you only become confused for a very short time - and the nyou'll get a wound + healing when it stops. The duration of Frenzy will not suffer. The self damage part of Berserker Frenzy cannot be shortend (it's directly tied to the frenzy duration) but iirc it will also give you wound + healing once Frenzy ends. With such a character you'd also need a lot of Health and a pet with heal on kill is very benefical here, too.
---
With all those I would recommend using Tuotilo's Palm and a weapon that does other damage than only crush (so no clubs and maces). For Skald Sasha's Singing Scimitar seems like the obvious choice. With Swift Flurry: Stalker's Patience (with Mercy Strike!) as well as Mohora Tanga (super high chance for crit chains because Red Flag Flying can proc itself!) are excellent choices. Watch out: Mohora Tanga can crash the game if your accuracy is much higher than your enemies' defenses (beause an endless loop of crits can occur that will shut the game down immediately without warning). If you don't overdo it with the accuracy/debuffing enememies defenses you should be fine though.
---
Best use would be both of serafen's mortars. hybrid use (1 melee + one ranged weapon) if often just worse than 1 dedicated melee set + 1 pure ranged weapon set. You can def. keep up the distraction if you don't use Clarity of Agony too often - because you will be shooting/reloading superfast with Swift Strikes + Streetfighter's passive. And Mortar's AoE + INT + Stunning Surge is an excellent, excellent combo. High INT also makes sure the distraction lasts long enough even if your RES is very high. On the otehr hand using a ranged setup is a bit detrimental to the FF attack. I suppose one can use it as a great way to dispose of enemies who come near you though. You don't even need to switch weapon sets in order to deal melee damage then.
Blunderbuss + melee weapon can make sense with FIghters (Clear Out can use the Blunderbuss if it's in the main had when a melee weapon is in the offhand), Rangers (Whirling Strike) works the same, Barbarians (Heart of Fury works with ranged and melee weapons, both will execute no matter what). If you count Blunderbus + bashing shield a ranged + melee setup it can make good sense for a lot of characters because you get the defensive bonus AND the dual wielding bonus that also speeds up the reloading. But usually I think pure ranged or pure melee beats hybrid in most cases.