I haven't bought a kit from ebay, 'cos i get a better deal from local spare parts shop(Burson), and if there're any issues you can return the unused item. Judging from the ebay pictures, I suspected it is basically the same kit sold on spare part shops, but you're saying that is NOT the case. Accelerator pump plunger was made of leather in the repair kit I bought from Burson. The original one was rubber, but it appears the leather plunger is working ok. They may get too dry in an LPG running carby, so it's important to run on petrol for few minutes a day or so to get it soaked with petrol. This is true for the whole carby, not the just the accelerator plunger.
With the gaskets, use "White Lithiim grease" on both sides of the gasket to help it seat better. Paper gaskets collapse over time and start leaking, so using lithium grease is a good way to remedy that issue.
If you're not happy, return it for a refund. Fleabay refund policy should apply to those items.
BTW, I learnt to cut the gaskets(all of them, including the more difficult main body/float bowl one) myself to prevent from having to buy repair kits to replace gaskets each time I open the carby. Also I should mention, lithium grease helps preventing the break down of the paper gasket, so you can use the old gasket again.
Search my carby threads to find out how to cut the gaskets DIY.