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Doggit
There was obviously something in the floor, but as it's gone, worry more about getting replacement tiles. But you could look at the wall outside, and see if there's any evidence. As to the kitchen, am I right in thinking that's a gas water heater on the wall; if it is, reckon to change it for an electric water heater, either instant type, or 15ltr store. As to the wooden beam, body or wood filler will strengthen the beam, but you could try asking the seller why it was done.
Best of luck, it looks like it'll be fun
Best of luck, it looks like it'll be fun