I would buy the latest version of iPad you can afford, the early versions no longer update to the latest Ios software (different cpu chips). I would be wary of buying one via eBay unless you are absolutely sure of what you are doing, when spending that amount of money better somewhere like CEX where you get a guarantee and can take it back if it doesn't work, YMMV.
As regards the adapter, unlikely you would get one as you describe. There are third party adapters for sd cards but Apple's attitude is if you want that functionality you should buy a Macbook.