For the rest, you probably know it is possible to dive in order to get some speed and then to pull up to perform flare, many pilots do it on a light aircraft on a regular basis, there is no reason why it would be impossible on a large aircraft.
Err no, all you do is end up going down faster for a minor increase in speed that won't help in the slightest during the recovery from the ensuing even steeper g-ravity descent towards earth (or water, as the case may be)...