Well yes, it seems like a lot of deliveries, but to be honest the first 3 are pretty much slight variatons of each other, the arm ball is a must have, the only majorly different ones are the carrom ball which is pretty easy to bowl because i have long strong fingers, and the "flying saucer" which I'm just not bothering with at the moment, might not either unless I find the need to use it once I play competitive cricket.
Top-spinner isn't that hard to bowl as long as I get really tall and fully extend my arm, the doosra in theory is just a few degrees more of wrist angle, but I can't bowl it with a conventional grip, I use more of my curled up and tucked index finger to give it a tweak while having my wrist as far as it can go the other way (which isn't far enough to bowl it with ease)
Besides, since I first posted that I started developing serious wrist pain, so much so my right hand ended up swollen and my fingers looking like sausages, I suspected carpal tunnel syndrome, and waited for it to ease away and so it did in 3 days, not bowling a doosra ever again, just trying to disguise my carrom ball better, saves the pain.
Thanks though for your help.
Been reading quite a bit and decided to register.
I am an left arm orthodox bowler and I don't bother with the doosra. I use the carrom ball to get the ball turning into the RHB. The saucer ball you describe sounds like what I call the "UFD" (wordplay on UFO) and I find it to be a very effective delivery. If executed correctly the ball will drift away from a RHB and skid/straighten. Very effective against a defensive batsman especially those that are leaving the stock balls that are pitched on off/middle stump.
Along with that I also bowl a wrong'un (googly), topspin and a legspin (looks the same as the googly) with the wrist for extra confusion against batsman that are trying to hold up an end.
The reason I steer clear of the doosra is because of the stress on the wrist that goes along with it, and the carram ball (and sometimes the UFD) has the same desired effect.