Hi Rover,
Congrats on your 5$ IIa!
I ebayed my first II from the fifties from the US becuase it was way cheaper that the ones in Europe.
The IIa is beautifully designed masterpiece, it has a great F2/50 Millimeter lens I just checked that a few hours ago. The only thing I don't like is the smallrngefinder. The engineeers themselves also seem to have thought sdo as they provided a sportsfinder, with some kind of paralaxx control. On the IIa you als can still choose the shutter speeds between the marked ones.
The IIc looks a bit clumsier but it somehow handles better. Ther isn't this stirdy button to open it on the upper side of trhe chassis, but a rather fragile looking thing tha would belong to a purse....but strangely I've never seen those damaged. The "strange" fil transport lever? Get used to it as you can use your expertise on other great Retina Rangefinders like the IIc/IIIC, the IIC, the IIIS and the undervalued IIS. I used my IIc a lot a sa back up and never had a problem because of the 2,8. The viewfinder has the 5omm frameline in it (unfortunately without parallay correction). Some of those view/rangefinders can be quite hazy and the framelines nearly not visible. The only reason to buy a IIIc would be for one f stop as the lightmeter often does not give exact measures. Besides IIIc/IIICs often command huge amounts at least in Austria, Germnay Switzerland and Italy.
The IIC is really an improvement! The viewfinder is pralllaxcorrected alsa a bit overcrowded becuase you have the framelines for the 50mm, the 35 and the 80 mm in it all the time.
Yes the IIc/IIC have several lense at their disposal. When you start using them you'll find yourself at their disposal. they are cumbersome and in the first time of use you will be bound to a very static routine of taking pictures with them. If it's additional lenses you want get a IIIS - the camera that challenged the Leica (Which isn't so ridiculous a thought as The OPorsche 356 also was just a tuned up VW Beetle under its skin.
Well good night I hope that was enogh information for your next 3 no four acquisitions (a IIc,a IIIc a IIC and a IIIS and.......