1)
What is the meaning of "ki'S'enei ha'Bakuros"?
1.
Rashi: They ripened fully at the beginning of the time of the first figs. They are dear to one who finds them at their beginning. Radak - this is like it says "k'Bikurah vi'S'enah b'Reishisah Ra'isi Avoseichem" (Hoshe'a 9:10).
2.
Malbim: If one does not pick a fig immediately when it first ripens, it gets wormy due to the sun (Shir ha'Shirim Rabah 6:2, 1). This is a metaphor for Galus Yehoyachin, who was taken first from Eretz Yisrael.
2)
How can ki'S'enei be Samuch to ha'Bakuros (an adjective)?
1.
Radak: It is as if it says ki'S'enei Atzei ha'S'eneah ha'Mevakros. Ki'S'enei is Samuch to Etzim.