As others have said, if you want a RIS or RAS, request it; the controller will tell you if he is unable to provide it. At our unit FIS's are just that: very low priority and unlikely to get much apart from 'report leaving the frequency'.
Someone requesting a radar service is a higher priority and we will do our level best to provide a radar service, even if it is limited. ATC recognise it's importance in raising safety levels for all concerned, so should you.
And on weather conditions - one's persona VMC is another persons IMC, and vice versa. It is all about the perception of the pilots concerned. It is no good saying 'Pilot A said he was VFR, therefore anyone else in the area saying they are IMC is wrong, and therefore must also be VMC in that area'. However if a pilot says he is IMC it gives you the heads up that all may not be gin clear in an area.
Back to the original question, you can also address the IFR plan to units that you will talk to OCAS (as well as the IFPS). Sometimes these will be picked up at the units that you will be wanting to talk to them, but is not guaranteed to, as a strip would not be printed out automatically )not departure or destination) and the FPL may not be seen/acted on unless the ATCA is looking out for such details.