Hi - yes the Shopify native solution is not available in the UK currently. But there are loads of 3rd party solutions that you can use. Two to check out are Codisto and DataFeedWatch, but as I say there are lots. DataFeedWatch is one of the cheaper options.
I tried quite a few out before settling on Codisto (we sell on eBay & Amazon in various countries).
Yes you can. Don't think the reply given is correct. I've just joined shopify to do exactly that. There is a totally free app within shopify already and it's hosted by ebay themselves and its for the UK. Just look for it within your sales channels in shopify. It will link all of your SHOPIFY listing to eBay and upload them as well keeping both in real time sync. But it will NOT download or list your ebay listings TO shopify. There is a paid 3rd party app for that which I used once then cancelled subscription cost me about £12 to import the once. I have also linked all products to my point of sale system so keeping 3 channels synced. Took me a couple of days to get it all running but all works great. So yes it is possible just do a bit of Google work