Does reindexing mean re-verifying each block?
Essentially, yes... The short answer is that it starts at the beginning and verifies the block data stored on disk. If an invalid block/file is encountered, it will start syncing (downloading blocks from peers) from that point to ensure the validity of all the blocks.
Question: Will my electrum server be personal or public? I want to provide in the peer discovery of the electrum servers (that run over Tor).
I'm not sure if the .onion servers are included in peer discovery or if you have to explicitly set them. The
Electrum docs regarding Tor seems to indicate that you have to either set up as connecting to 1 server (ie. .onion only) or you run the risk of actually connecting to clearnet peers for blockheader download:
Thus the two different options are, Connect to 1 server ONLY and get block headers and transaction info from that server. Or Connect to 8 block header servers and connect to 1 .onion server for the general use.
However, when I look through the list of "known" servers... I so see a couple of .onion servers listed:

So, it's possible that .onion nodes are included in peer discovery.
Note: Setting Electrum to use my Umbrel node (from a remote location)... it is connecting to my .onion address, but the other connected nodes are all clearnet.