Right after payment a Steam trade offer goes to the trade URL you enter at checkout. Typical time from payment to offer is under 5 minutes.

Yes. Stay logged in to Steam after you pay. The offer arrives within minutes and you accept it there. Missed it? Check pending offers in Steam, then write to support with your order number.

A hold Valve puts on items that changed hands recently. It ends on its own, up to 7 days after the last trade. A locked item cannot be sent until then; the offer goes out when the lock ends.

The float on the item page comes from the lot's inspect data, and the wear bar shows where it sits inside its exterior. Check it there before you buy.

The methods available right now are listed at checkout, on the payment step. Prices are in EUR.

If the item has not been delivered to your Steam account yet, yes, in full. After the trade is accepted on Steam, sales are final. See the refund policy for details.