-If you just want to play games I would suggest a CD32. Just insert a CD and play. You can buy many original games on ebay or find games compilation CD's on the net in ISO format with hundreds of games (even A500 and A1200 games not released on CD32 too). Download, burn and play.
If you want more than playing, or you want a "retro computer" feeling, both A500 and A1200 is a good way to start. A1200 is nearly 99% compatible with the A500. You will hardly find any software that will not run on the A1200 and there are many AGA chipset only games/demos that will run only on the A1200. So I would prefer the A1200.
-Regarding NTSC I cannot help, I always used PAL machines, and most software is for PAL, but if I'm correct you can select on boot between PAL/NTSC mode so it's not an issue.
-Transferring ADF images is not trivial but there are many methods. In case of A1200 the task is easier as it has more memory and OS3.0 has support for PC formatted floppies (CrossDos).
If you want to transfer only a few images at once I would do the following:
1. format a disk to 720kb on PC
2. transfer lha or unzip decompressing utility and adf2disk utility to amiga's ram
3. compress the adf on pc and copy it to the disk (compressing is necessary as amiga's floppy size is 880kb so it will not fit the 720kb disk)
alternatively you can split the file into two and join in amiga side.
4. decompress the file to amiga's ram disk
5. write it to a new amiga floppy disk with adf2disk.
In case of A500 this way is no go, as it has only 512 or 1mb ram. The A1200 has 2mb.
If you want to transfer more files, this method is quite slow and exhausting. I would suggest to buy a PCMCIA Compact Flash adapter. Copy all the files to the CF card on PC and plug it to the PCMCIA port of the A1200. That's all.
There are other methods using serial cable and AmigaExplorer software or buying a PCMCIA ethernet card and building a network between the Amiga and the PC, or using a PCMCIA CDROM, etc.
Edit: I see the others were faster. Indeed, adding a hard drive (any old 2.5" laptop drive smaller than 4Gb would do the trick) and a PCMCIA network card would make the best experience. You can download all the games from the net right on the amiga and play them from the hard drive. No need to swap floppies
