Woof All:
1) In my understanding numbering systems are not the same thing as striking patterns/combinations, although some combinations are usually found in numbering systems. The numbers are but a way of naming strikes.
There are some differences in numbering systems. Systems around lighter weapons tend to have a 2 on the diagonal, whereas in systems around bigger weapons it is more common to see the 2 come back on the mid-horizontal. PT has 1 and 2 as horizontals to the head. In my experience, many systems install the horizontal strikes only on the mid-lines and typically practitioners so trained often lack the horizontal on the head line.
In DBMA we prefer to simply name strikes with combinations of these words: Forehand, Backhand, Redondo, Slash, jab, vertical, diagonal, horizontal, uppercut, thrust, and punyo, reverse, etc. (Kabaroan Eskrima has an analogous manner of naming its strikes that is more evolved.) Thus for example, a backhand vertical jab, a forehand slash uppercut, a reverse forehand redondo, etc. Occasionally strikes have their own name e.g. the Caveman, the Dodger, the Bolo, etc.
Combinations are addressed directly as such.
2)Concerning when to start sparring/fighting: It depends not only on the individual, but also on the level, attitude and composure of whom he is fighting.
The advantage to starting relatively soon is that it tends to innoculate one against martial arts fantasies and promotes getting the essence from training.
The potential disadvantages are:
a) that it plays to the vanity of the player i.e. thinking himself a badass, he becomes too opinionated about training methods and techniques and may lessen his willingness to engage in mid and long term skill development, and
b) he may get dinged and put his tail between his legs because the experience overwhelmed him.
Woof,
Guro Crafty