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I'm new to astronomy myself, and recently thought the same questions. First off you ask "are there good ones and bad ones" and the answer is yes, to everything. Good and bad scopes, mounts, filters, eyepieces, cameras, camera lenses etc. Getting glass with the perfect optical qualities is more difficult than glass that's just ok. So deciding on how much quality you can afford is the key.
As for eyepieces I bought myself 8mm and 21mm Baader Hyperions. They are awesome compared to the kit eyepieces that came with my (cheap) scopes. They can be used in both 1.25" and 2" focusers and give a nice wide field of view which I find helpful for finding my way around the sky manually. There is a Baader Hyperion zoom eyepiece (8-24mm I think) which is under $400 and from what I've read its quality is just as good as the individual eyepieces. So a nice zoom like this might be the way to go, it covers pretty much the whole range you'll need and if later on you want to buy one or two ultra high quality single EPs you'll have a better idea of what range you usually use the zoom at.
If you go with single EPs I'd recommend something wide (around 20mm) for larger targets and to help find targets, and something under 10mm for more magnification. The specs for your scope should list the maximum practical magnification, divide your focal length (1,800) by the max magnification and that should give you the smallest EP you should consider.
There are also barlows to throw into the mix. A barlow gives added magnification and generally come in 2x and 3x varieties (but there are others). So with a 2x barlow my 8mm and 21mm can become 4mm and 10.5mm. So getting a high quality barlow you can essentially double your eyepiece collection. So try to look at two eyepiece lengths that when used with a barlow give you a nice even spread of choices. For example getting a 5mm, 10mm and 2x barlow would be a waste because the 10mm would become a 5mm so you don't get any extra flexibility for all the gear.
Not sure on the planetary filter side but it seems a good starting filter to get (I'm saving for mine) is the Astronomik UHC filter to help cut through light polution and help bring out nebulae etc. There are also other filters more specialised but they seem to be of use for smaller subsets of targets (and especially for better astrophotography). The Astronomik UHC seems to be the best first choice all-rounder filter, but perhaps for your scope a O III Group A filter would be a better first choice (I'm sure others will be able to better advise).
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