I grew some last year and although I planted a few seeds I only ended up with one plant, however, it ended up growing in my greenhouse in a 12" pot and grew to about 3 feet high and the same across.
They ended up a lovely dark green colour which were a fairly hot pepper measuring approx 3" long and just over 1" at the shoulder.
I didnt count how many I got off the plant but I did manage to get 4 large jars full of sliced and pickled Jalapeno's.... very tasty too!
This year though I couldn't grow them to save my life