In IL everyone needs a FOID-- 10 bucks and a form/photo sent in good for 10 years. Details and forms on ISP website.
The new CCW requires a 16 hr course or proof of equal training. Cost is 150 bucks/ 3 years. Also see ISP website.
Chicago proper has an AWB in effect and bans mags of 10+ capacity. The gun registry is now defunct so 'common' non-AWB type guns are free and clear with a FOID. If carrying a Hi Cap Pistol in Chi w/ Hi cap Mag on an IL CCW you'd be spot-on OK as the State law included preemption. Cook Co. also has an AWB and bans 10+ cap mags also.
Understand that in practice I have never heard of anyone actually being prosecuted for the AWB or Hi Cap mag ban in Chi or suburban Cook. There are no gun store in Chicago (for now), but are some in suburban Cook that can't sell AWB listed weapons or hi cap mags.
All of this boils down to the fact that you MUST have a FOID and need to be mindful of the Chi and Cook, Co. laws. Outside of Cook you can buy most anything save for class III stuff (apart from SBR's and AOW's), some banned ammo: AP (except for m2 .30/06 and ss 109 5.56 as it is exempted), bolo, flachette and dragon's breath shotshell. Again, the ISP has this info.
In a nutshell, living in IL isn't nearly the nightmare for us gun nuts that many folks think it to be. The tide has been really turning our way in the last few years thanks to the hard work of legal teams and the NRA / ISRA and other folks.