How is Frieza 100 times stronger than SSJB Goku from the Broly movie?
Ikari Broly = SSJB Goku (it was confirmed that they were equal in strength, Broly probably just didn't have the skill to keep up)
SSJ Ikari Broly = 50x SSJB Goku, which makes it understandable that he effortlessly powered through the combined blast of 2 Super Saiyans
2x SSJB < Golden Frieza < SSJB Broly.
Frieza could possibly out-stamina Piccolo, but he has a healing factor.
Frieza also won't be fully serious at first due to his arrogance.
Ikari Broly = SSGSS Goku
SSGSS Goku + SSGSS Vegeta < SSJ Ikari Broly
Golden Frieza =< SSJ Ikari Broly
Broly was able to no sell a combined Galick Kamehameha from both Goku and Vegeta combined and should be 50 times superior to both of them individually if not more due to his RE
Frieza's normal punches were strong enough to force Broly to dodge, and could keep up with Broly for a straight hour before being overwhelmed
I def admit I'm wrong about the x100 thing, but it should be x50 instead due to SSJ Ikari Broly simply stacking Super Saiyan on top of his Ikari form
Frieza should backscale to that due to being able to injure Broly. This should be a less than 25% decrease due to the aforementioned Vegeta vs Cui example. Cui was only 25% less powerful than Vegeta, yet he couldn't hurt Vegeta in any meaningful way
This means that Frieza is still at the end of the day possibly dozens of times stronger than Goku and Vegeta
As for your other points:
Piccolo's healing factor does jack shit unless he loses a limb. Frieza was able to 1 shot him in RoF by piercing his heart
Frieza has fought Piccolo several times before, and unlike his Namek iteration, is capable of sensing ki and isn't nearly as arrogant as before. In fact, he was more than willing to swallow his pride and train after the ToP so he wouldn't die again
Even if you argue thast Frieza will be arrogant in the beginning, once he takes 1 hit from Piccolo (which he will survive due to Type 2 Immortality), he'll just kill Piccolo afterwards
Heck if you really want to wank the shit out of Frieza, you can even say that Frieza matched Broly's RE for an hour and kept getting stronger alongside Broly, full on Garou style, before getting outscaled himself. If you believe that to be the case, then Frieza just outgrows Piccolo within minutes