what information does the seller see ? the bidders max bid . etc. ?

When you place a bid, the only info the seller sees is your name, feedback rank and what the high bid is. The only way they see your max bid is AFTER you have been outbid by someone else. Example: Your max bid is $15.00. The starting bid is $5.00. You bid, it shows you winning at $5.00. Someone else comes along, bids $16.00, the bid will keep jumping over yours to the other buyers max bid of $16.00- this revels that your LAST bid is $15.00, so that must have been your max. The seller cannot see the max bid any other way than this.

The seller can see all of the bidders' actual IDs, but he doesn't get any extra information about the bids that have been placed.

The pricing information that you see in a bid history is the same info that the seller sees. He does not see your maximum bid, unless somebody outbids you, or comes within one bid increment below your bid -- same as what everybody else can see.