I'm sure the old Camra and David Line books I'm still using advocate adding a teaspoon of salt as a addition per 5 galls. Have to say I've never bothered in my 30 years of brewing. But I'm sure at that level it won't do any harm and the results reported will be found at those quantities.
Hi I'm in Billericay. On the lemon wine, I made one a couple of years ago, it was very dry and the sharpness of the lemons was a little too much. Still drank it though.