To Exactly answer your questions:
Is it possible, Does anyone know the process?
Yes, you would have to ferment some wine then add a very high ABV% of Alcohol, acquired, paid or distilled by another means.
300ml of 10% wine + 700ml of 80% spirit = 59%ABV
How much yeast, should I use in the grape juice?
Go for 1 tsp per gallon(4.5L).
can I convert baking yeast to brewer’s yeast?
No they are different strains, but bakers yeast will make alcohol.
Can I add liquid ginger in grapes juice?
Yes, you are drinking it, you add whatever you like.
How do I know if my wine is unfit for drinking?
Typically is smells bad, tastes bad or has a visible infection growing in it. I believe (please correct me guys) typically there is nothing harmful to humans that can grow in brewed beverages, but will taste terrible.
Please look around, including this site grow your knowledge, and feel free to ask more questions. If 60% ABV is your goal, I would direct you to HomeDistillers for achieving this, (please forgive me homeDistillers!)
I downvoted your question, because I believe you are missing some huge fundamentals, require some online reading and I don't believe you question is improving question catalogue. Also this approach will lead to some terrible tasting drink.