3. The Gemara says that if not for the posuk saying shemita, we might think that the seventh year is counted from now.
Rashi says that the 7 years of kibush and 7 years of chiluk intervened. However, that would still come out the same year as shemita, unless you factor in yovel, in which case it's ikar chaser min hasefer
The Kollel replies:
"Now" was in Arvos Moav, which was the fortieth year and would have thrown the count off by one.
Dov Zupnik