Is Mr. Sinister actually a mutant?

No, it makes him a mutate.

Nope, he's just freakin awesome.

human mutant , like omega red or deadpool

" No, it makes him a mutate. "

Omega Red was born as a mutant....when he matured his deathspore virus activated and everybody started dieing around him...... 
He decided to be a serial killer.
Eventually he was caught by Banshee when Sean was working for the Interpol......
"Somehow" he ended up in weapon X program where they outfitted him with carbonadium coils to control his deathspore virus....
 

" No, it makes him a mutate. "

" @Edamame:  No....your right the KGB gave him his coils(I mixed this one with an alternative version)....and death-spore is actually his Death Factor (Also mixed my realities..) About being the child-r., I do not remember...I remember however how Banishee was disgusted in the way that Arkady had a perverse joy in killing innocents..... "

I wonder how far into his body the Carbonadium tentacles go. Just up into his arms?  And is the Carbonadium armor stuck onto him?  

" @Ransack said:

" @Edamame: You're right. Over the past century or so, Sinister mutated himself even further by splicing the genes of other mutants into his system, but he is still a mutant first and foremost. His x-gene was activated by Apocalypse, but does that make him less of a mutant? "

No. Sinister is not a mutant. He was a human geneticist and became a mutate through aforementioned methods and processes.  I am not sure why you think that Sinister is a mutant. Are you thinking about the mutant named Exodus whose powers Apocalypse activated? "

If sinister is mutate why in first to last was he identified as a potential leader for the mutant race.

has he and or she or neither been reborn. That could take some effect.

He got touched by apocalypse while strapped to a table

Sinister received his powers in two ways one genetic manipulation done to him by Apocalpyse and secondly genetic splicing he did to himself using DNA samples from mutants, he isn't a mutant at all & as for Exodus he is a mutant that had his abilities awoken by Apocalpyse. As for Omega Red he is also a mutant, he had his abilities augmented by the Soviets though & had the carbonadium tentacles attached to him.