The term Planetary nebula can be very confusing. It has nothing to do with planets. They are the atmosphere of dying stars like our sun will be in 5 billion years that has been cast off and is expanding. The best filter to use with these is an OIII as that is the light band that is emitted strongly by most PNs. A UHC filter will help with dim ones (NGC 7293 the Helix for example) but most are reasonably bright. Many are however quite small and appear as stars rather than discs, so "blinking" an OIII can help pick them out.
The "halo" around Saturn is most likely light scatter from a bright object, maybe excerbated by haze in the atmosphere or condensation on optics?
Not sure about the "clown" nebula? Do you have a catalogue number (NGC for example) for it?
As a rule it is often a good idea to use catalogue numbers followed by a popular name as some "popular" names are not well known and there are duplicates. For example the "Saucepan" refers to Orions belt and sword here is Austrlia but to the Big Dipper in the northern hemisphere (or at least it did when I was a child in the UK) and that is also known as the Plough. There are at least 2 galaxies called the Hamburger that I know of.
Actually I have just had a thought! maybe you mean the "Clown Face" nebula? That is more popularly known as the Eskimo nebula and properly as NGC 2392 (see
http://en.wikipedia.org/wiki/Eskimo_Nebula )
Yes you should be able to find it if the Twins (the stars Castor and Pollux) are visible. Finding it is really easy but remember it is small!
First locate Wasat or Delta Geminorum in your finder, then move your scope about 2 degrees roughly east until you see another bright star with a dimmer companion just west of it, scan the area within 1 degree south of that star (to move south move your scope up in that part of the sky) with your main scope and you should find a "fuzzy"star with a dimmer star just north of it.
As I said it is small and you will need good seeing to tease much detail out at higher power. The central star is an easy get in my old 12".
Cheers
Malcolm