to get to buy mode you can hit F2 and to get to build mode use F3 or you could find the button on the bottom left corner that has a picture of a chair.
After you download it on The Sims 3 website at the exchange.
in buy mode
You can buy it in buy mode. its in the electronics where you find the computers.
yes you can ride in a taxi or a car you can buy a car in buy mode
select
You should see a chair under two outlined sims and above the paint thing on the lower bar. Click on it and use buy mode.
Go to the buy mode and go to the outdoor items and it should be there
There is no car lot, you buy the cars in buy mode.
In buy mode under kids, where else? XD
You can find a food proccesor on the buy mode on the sims 3, then you go into kitchen, then small appliances.
You can buy a potty in the kids section of "Buy Mode" under "Furniture" --Mr.Helper
press F2 or click buy mode