Hi,
1. As my guess your data source(prod) version or changes may not be synch with dev data source. thats why it may asking.
2.No. because you didn't change any thing on your data source. no issues as my guess.No imapcts on it. But During transport better keep your data load on hold at prod.
3. No and not at all. Thru transport we transports only structures not the data.
Thanks