1)
Why did Shlomo gather people?
1.
Malbim: (a) It was to be Mekadesh the Bayis via the Sanhedrin. (b) It was for the honor of the Aron.
2)
Why did Shlomo gather only the Zekenim [and leaders]? David gathered everyone (Divrei ha'Yamim I, 28:1), even the youths!
1.
'Rashi': Shlomo acted with more Chachmah than David.
