quid
I think some of your marbles may be on the ground.
1.The V speed concept applies for balanced as well as non-balanced take off performance calculations.
2. V1 goes up withe the weight as it is also related to V2 wich only depends on weight as it is in IAS wich equals EAS at low speeds and density altitudes. As long as there is enough runway ahead to stop it's OK to increase V1 with the weight.
3.As far as Vmcg is concerned:
Regulations do not require that x-wind is taken into account.
If one day this would become a requirement then the case of the most critical engine (similar concept like on the piston thing) would be applicable, hence it would not matter wich engine would fail.
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Smooth Trimmer