I should have answered your questions - just get off and mow as long as you hold the left handle which is the OPC. Deck up deck down does not matter. There is no OPC on the deck.
Cost - I just paid 6950 out the door for a 48 vride about 2 weeks ago. Tax is 9.25% where I bought it - so 6950 minus whatever the tax is that I paid, is how much the mower was.
One dealer got stuck on the 7150 price and I called some others in 100 mile radius until someone gave me a better price - luckily it was only 20 miles away.
It will tear up some turf with new tires and the controls are sensitive. But someone with more experience would be able to handle it better than me.