Hi Paula
Well the weather in Rhodes is usually pretty good in May, not unsimilar to Cyprus as the island is the furthest south. Days are normally excellent for sunbathing (nice n hot but not uncomfortable). It can cool down a bit at night, so take a light jacket or a couple of long sleeved t-shirts just incase but i've known some very warm nights even in May. The only downside on holidaying so early in the year is the sea hasn't had chance to warm up and can be quite cool (hasn't stopped me yet though!).
Lardos is a very small, quiet resort so might be a bit of a culture shock if you're used to Paphos but Lindos is a livelier, good sized resort and it's only a short distance away by bus or taxi.
If you enjoy Paphos do visit Rhodes Town - i'm sure you'll love it. It's a good distance from Lardos but easy to reach by local bus or hire a car and visit some of the attractions such as Seven Springs en-route.