1_Would you please elaborate on it more.
2_Would you please keep my spot(or seat)? I'll come back.
I don't know about "true". Can questions be true? But #1 is OK (correct) as is #2, but in #2 I would use "spot" for a place in/on line/queue; for a seat you could also use "save" for "keep". Finally, you could also use "be" in place of "come".