Thread being pulled to the top can EITHER be bottom tension too loose OR top tension too tight. If top thread is breaking, I'd definitely start with the latter and adjust the top tension.
Which needle to use depends on the thread used AND which sandwich is used. Different fabrics such as batiks or thicker batting will dictate that you use a larger needle. Definitely if the thread calls for a 90/14 needle, use a 90/14 needle.