Berklee online has this free 4 week course that just started. I think its not too late to sign up.
> Do I need to buy a synth?
pretty much all DAWs, like Abelton, come with softsynths (software based synthesizers). there are many others that are available for free in VST format, which can be integrated into abelton or other DAWs. I would really recommend getting your feet wet with those. you may prefer softsynths over hardware synths, and even if not, softsynths will let you try many different types and synths with different features.
not necessary. some MIDI controllers include drum pads. there are many DAWS and VSTs that have on screen drum pads, but I think most producers simply input their beats with the sequencer/piano roll. drum pads can still be useful for triggering loops during live performance, or for general MIDI use. by all means, if its in your budget and you just want one, go for it, but otherwise, its really not needed.
not absolutely necessary either, but I would recommend one. it makes it a lot easier to try various presets for your softsynths, as well as noodling/jamming to create your groove. its also nice for recording real time modulation automation.
Searching for guidance, thanks!