iPad mini2: I don't know. Someone else will have to answer this.
Limits on varieties: I don't think there's a limit, at least not for practical purposes. Your patience looking through those varieties is probably the limit.
Short Answer: Whether or not those varieties count toward your inventory in stock depends on how you do it. If you choose to set each size and color as a variety, then you can choose to keep track of your inventory for each of them separately. If you set the sizes and colors as modifiers, then it would just track the inventory of that item as a whole.
Long Answer by Example: You sell widgets. Each widget comes in blue, red, green, yellow, and white. You have 100 widgets in stock. You have 20 large widgets (4 of each color), 45 medium widgets (9 of each color), and 35 small widgets (7 of each color). Below are Options A, B, and C for how you can set this up.
Option A: Set this up as one item (widgets) with 100 in stock with a modifier for size (large, medium, small) and a modifier for color (blue, red, green, yellow, white). When you sell a large blue widget you will select the widget item, the large size modifier, and the blue color modifier. It will be subtracted from the total inventory so you are left with 99 total widgets. When you look at your inventory, you will know only the total number of widgets you have, and neither the sizes nor the colors that are remaining.
Option B: Set this up as one item (widgets) with three price points (20 large, 45 medium, 35 small) and a modifier for color (blue, red, green, yellow, white). When you sell a large blue widget you will select the price point for a large widget and the blue color modifier. It will be subtracted from the large widget inventory so you are left with 19 large, 45 medium, and 35 small widgets. When you look at your inventory, you will know how many widgets you have of each size, but you will not know which colors they are.
Option C: Set this up as one item (widgets) with fifteen price points (4 large blue, 4 large red, 4 large green, 9 medium yellow, 7 small white, et cetera) and no modifiers. When you sell a large blue widget you will select the price point for large blue widget. It will be subtracted from the large blue widget inventory so you are left with 3 large blue, 4 large red, 9 medium yellow, et cetera. When you look at your inventory, you will know how many widgets you have of each size and color.
