Yes it is an adverb. It means in a tentative (slow and careful) way.
Tentatively is an adverb.
No. Tentatively is an adverb formed from the adjective tentative by adding -ly.
You would say "tentatively August 6, 2016." The adverb "tentatively" modifies the date, indicating that it is not a confirmed date but rather a provisional one. Using "tentative" as an adjective would not be grammatically correct in this context.
The adverb form is "cautiously" (carefully, tentatively). The related noun is circumspection, meaning caution or prudence.
Based upon my somewhat limited information, I can only answer your question tentatively. The meeting has been tentatively scheduled for this Friday at 10:00 a.m.
He moved tentatively across the ice...
The opening of the store was tentatively scheduled for late August.
The meeting was tentatively agreed to -before I checked my schedule! The evening news programs are always tentatively scheduled when they follow a sporting event.
tentatively
The surgery is tentatively scheduled for next month, but we'll do it sooner if you're in a lot of pain.
No.
John tentatively peeked under his bed because checking for monsters always made him uneasy.