I've done this ride and in planning my travels shared some of your questions regarding route specifics. Ultimately, my final route selection was determined by a differential interpretation between the generic in-state rules (You may take any route you like - but remember you may not leave the State) and the specific, added DBR requirements for the unique Ride Around New York
http://www.ironbutt.com/themerides/nys/index.html (see below with DBR requirements emphasized)
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You must obtain DBR in the following jurisdictions and at least every 350 miles. The receipt MUST indicate the city, date and time. Check your receipts.
Newburgh area;
Champlain;
Watertown;
Liverpool/Syracuse area (for example if west bound Warner Service Plaza just west of Liverpool on Thruway is acceptable);
Buffalo area (for example Angola Service Plaza just south of Buffalo on Thruway is acceptable); and
Jamestown.
CAUTION: I-86/NY-17 near Waverly crosses into Pennsylvania, you must take NY-17-C or some other route to stay inside New York.
You must obtain the receipts in the order listed. Either order (clock or counter-clock) is fine but they must be in order, e.g. Champlain MUST come immediately before or after Watertown. You may take any route you like - but remember you may not leave New York state
and the required DBRs must be acquired in order."
So, based on the differentiation between the generic in-state rules and the non-generic mandated DBR rules for the Ride Around New York, rightly or wrongly, I elected to follow the DBR route specifics listed in the Ride Around New York. I rode clockwise (Newburgh to Jamestown to Buffalo) and to avoid the Waverly, NY/South Waverly, PA accidental out-of-state crossover on Rt. 17, I went through Ithaca, NY, avoiding it all entirely.
I cannot speak to the availability of patches or any other in-state New York ride merchandise, but did receive a sweet all-in-state New York specific certificate with a color outline of NY state containing the state's logo--Excelsior!