The short answer is yes indeed, 3C Polymer Sealant can be used on areas that are either damp from overnight dew or from rain (even whilst it's raining) this is in stark contrast to silicones and the older technology of polysuphides that require substrates/surfaces to be bone dry upon application. The benefit of this fact is the continuation of work in all conditions and confidence in the adhesion of each application. 

The industry has gradually moved away from polysulphide sealants in favour of modern hybrid polymer sealants such as 3C Polymer Sealant for several reasons, but perhaps most importantly, this newer technology is far superior from an environmental & health point of view. Whilst polysulphides have a poor profile for health & safety due to their solvents and thus have quite a rank odour and shorter shelf-life, the modern chemistry involved with the production of hybrid polymers is considerably less hazardous and longer-lasting both on the shelf and after application. Three very strong arguments for the use of hybrid polymer sealants versus the historic polysulphide sealants are:

1) Superior adhesion that hybrid polymer sealants exhibit on various substrates/surfaces.

2) The excellent UV stability that hybrid polymer sealants show when weathered.

3) Hybrid polymer sealants are solvent-free and practically odourless.

Unlike silicone sealants that can suffer from poor adhesion on certain materials, hybrid polymer products such as 3C Polymer Sealant are much more forgiving when it comes to adhering to the varying porosity of substrates/surfaces giving an all together wider scope of applications with considerably better grab onto the sides of the joints. A primer is very seldom used when using hybrid polymer sealants.

3C Polymer can indeed be overpainted with oil based paints. These types of paint products form a seal around the applied sealant and can often stop moisture permeating which can slow the curing process so allowing the Polymer to cure as much as time allows is recommended. As always when unsure, a small test spot of the chosen oil-based paint on the sealant to see how it's received is a good idea!