I think Logic Pro (Mac) is your best option if you're able to use it. It basically can do everything you need it to do. (Make beats, record live instruments, vocals etc.) And it does all pretty well. The stock plug-ins are really dope. I record a lot of musicians and just throw some stock plug-ins on em and with some very minor tweaking I'm set. The synths built in to the program are actually pretty good. To get the dubstep bass (the wah-wah/wub-wub.) You're going to have to learn how to essentially create them from scratch. Which is exactly what you have to do if you want to earn any respect. Part of what makes you a respected dub-step artist is doing the whole 8 different bass sounds in one track thing and your music will get very repetitive if you just used stock sounds. However NI Massive has some dope stuff to use since you're just now learning (which you'd use as a plugin with Logic Pro.)
Once you get a little more confident in your beat making skills. I'd say get a Native Instruments Maschine and some type of Midi Controller. Using those in tangent with Logic Pro and Massive is going to give you a whole new level of flexibility and make electronic music creation just sooo much easier for you.
Take the time to watch this video. It'll kind of show you what I'm getting at.