that I worship a different Christ and/or a different Holy Trinity than what Orthodox Christians worship.
This isn't really accurate. There is no other Christ or Holy Trinity to worship. You are directing your worship towards the Holy Trinity that you see in the Bible. But because you do not properly understand the Holy Trinity and are not mystically initiated in Orthodox Christianity you are not worshiping "in Spirit and Truth".
Is this actually the consensus amongst Orthodox Christians that all the non-Orthodox (heterodox) Christians are actually worshiping a false god rather than the One True God simply by having some doctrinal misunderstandings, or is this only the view of the minority that wish to be polemical?
I doubt there is a consensus. There are many teachings which exist in the Orthodox Church which lack consensus. Often they are regarded as the majority teaching of the Fathers without, often without contradiction. Often they are regarded as the logical implication of the explicit Tradition. So just because there is not a complete and explicit consensus does not mean that the teaching is not the
Again, I'd like to clarify that speaking of you worshiping a false god needs some major clarifications. Like I said, there really is no such thing as a false god, in the sense that no other deity actually exists other than God. Also, like I said, unlike heathens your worship is actually directed toward the personality in the Bible that we understand to be the Holy Trinity. So in this sense you are directing your worship towards the True God. The only issue is that you have perverted the teaching of the nature of God so that you conceive of a mutation of the True God.
Also, like I said before, it's not just an issue of the doctrinal misunderstandings, but also that you are not mystically initiated into the Church. Worshiping "in Spirit and Truth" appears in the Bible to be a Pentecostal charism of the Church.
If this is the Orthodox view, what is the fate of most of the heterodox if they remain heterodox? Are they more than likely going to hell or is it more likely that God will extend His mercy to them despite their flawed belief?
I don't think we can speculate whether the heterodox are more or less likely to go to Gehenna. How one will be judged is really about whether one loves God and His Creation. It is possible for a condition towards loving God to be indicated by love for His Creation. Of course being judged on love for God logically indicates that a heathen must accept Him when they finally realize Him for who He is. But I have a strong belief that there are many heathens who are disposed towards love for God and that that love will not be realized until they convert at the very last moment at the Second Coming.
Does the Roman Catholic Church believe that all heterodox Christians are worshiping a different God simply by being outside the True Church?
No, but you have a rather different conception of Baptism/Chrismation, so I don't think it's a fair comparison.