How long does it take to evolve a traded Pokemon If their evolution is..

Just because they grow faster doesn't mean their friendship will be any faster. If you have the Pokemon hold the soothe bell, and use status uppers on him, and using a few berries that increase their stats on him, the Pokemon should evolve in no time. You just need to train him, and never get him to lose/faint. Also, keep him in your team at all times, in case it does get slower.

Their friendship with you is at it's max when there are two big hearts on them, on the team friendship app on the Poketch.

I think that when you get someone out of a trade, like Riolu, that evolves with happiness, thier happiness resets. However long it takes you to raise it's happiness to a level where it will evolve depends on you and what you do with it

Rioulu evolves at lvl 30, reguardless of happiness. Well, it should take a little longer, depending on how the Trainer treated it. (as in making it happy). If it is happy with both hearts, jsut level it up to evolve it.

Well, depending on what you give to your Pokemon, it will adjust it's happyness accordingly. Normally, if no stat boosters/no battles/no massages/no Poffins, they will evolve around 25 or so. But if you give them regular massages, give them one or two of their favorite flavor of Poffin, and give them 10 of every stat booster, and make them hold a Soothe Bell, they can evolve as early as level 3.
P.S. You must follow all other requirements(if any) that that Pokemon may or may not have in order to evolve.