Esdra,
Thank you for the good questions.
I am quite familiar with church history and do not see a disconnect between Zurich and Geneva reformations, other than of course, Zwingli's psychological versus objective view of the Supper:
To eat the body of Christ sacramentally, if we wish to speak accurately, is to eat the body of Christ in heart and spirit with the accompaniment of the sacrament...You eat the body of Christ spiritually, though not sacramentally, every time you comfort your heart in its anxious query 'How will you be saved'...When you comfort yourself thus, I say, you eat his body spiritually, that is, you stand unterrified in God against all attacks of despair, through confidence in the humanity he took upon himself for you.
But when you come to the Lord's Supper with this spiritual participation and give thanks unto the Lord for his kindness, for the deliverance of your soul, through which you have been delivered from the destruction of despair, and for the pledge by which you have been made sure of everlasting blessedness, and along with the brethren partake of the bread and wine which are the symbols of the body of Christ, then you eat him sacramentally, in the proper sense of the term, when you do internally what you represent externally, when your heart is refreshed by this faith to which you bear witness by these symbols"
Src:
Fidei Expositio, Zwingli dated 1531, in
Reformed Confessions of the 16th and 17th Centuries pp.190-191.
Both Geneva and Zurich were staunch unconditional election proponents. I cannot answer your question about "double predestination" until you explain what you think that means. Given that you are a Roman Catholic, I cannot assume you are using the term as would a Presbyterian.
If you could review this:
"Double" Predestination by R.C. Sproul
And then get back to me about how you were using the term "double predestination" we could proceed. Barring that, the short answer is that both Geneva and Zurich affirmed double predestination, but neither affirmed any view that would be considered "equal ultimacy" in predestination (as discussed in Sproul's article). Such a view is
Hyper-Calvinistic--a minority view rejected by the Presbyterian majority.