Does the BP node really need a copy of the blockchain?

Folks, I’m wondering …

#1 How can I verify that the Relay can talk to the BP node (and vice versa)
#2 Does the BP node really need --database-path, --socket-path

In case the BP needs to have a --database-path, can this perhaps point to a shared drive with the Relay? That might be ok, if the BP only needs to do read ops.

Also, when the Relay is initially syncing I see

Chain extended, new tip: 0f921643a72bf2ac6cccc1ab965818976671099e011149b785b23504241cd282 at slot 9222990

There is no reference to an epoch nor can I find references to that slot number in the explorer. How many slots can I expect to get downloaded? Is it perhaps current epoch x 432000 => 101520000

cardano-cli query tip --mainnet
“blockNo”: 4913980,
“headerHash”: “2d429e91df381611dc4dd708318c19a507d3e4b2daa7a14bcfec86a6b2964927”,
“slotNo”: 13064627

The block number is given in the explorer

4913980 / 5076727 => 97%