Lift is always balanced by gravity. Upon takeoff, increasing the lift overcomes gravity. Upon landing, you reduce lift causing gravity to marginally overcome lift. The operative word here is 'marginally'.
Also note, the plane has to go nose-high on both takeoff and landing. It can't be completely horizontal and generate the required lift at takeoff speeds.
Yes, all commercial airliners have both leading and trailing edge flaps and some have slats (difference being with slats, the air flows between the slat and the wing as opposed to just being an extension of the wing). Typically, they are extended a quarter or halfway at takeoff and all the way at landing (a pilot can correct that for me...).