I think it's safe to assume anything suggested to start in the fall in a cold frame needs cold stratification. You can do that inside with your refrigerator or plant them in a flat and put them outside where they'll get some frost action. It depends on the plant your trying to grow... some things might need a few seasons before they'll germinate. I find that most things will germinate after 4-6 weeks of cold. Jilleto's has some good advice about stratifying seeds - http://www.jelitto.com/english/tips-e.htm#tip-goldkorn-e
Seeds that need to be planted as soon as they're ripe? ... again it would depend what they are. All you can do it try. Some seeds won't tolerate dry storage and will rot as soon as they come in contact with moisture. Many of them can still be germinated - you just may not have as good results as you would if they were fresh. Sometimes soaking the seeds will help hydrate them.
To Plant in situ? - That means plant them directly in the garden where you want them - These are usually plants that won't tolerate transplanting - Poppies are a prime example. Sometimes you can get around this by planting them in a peat pellet or newspaper pots. This limits the transplant shock because you plant the whole pot in the ground. Some things just perform better though if they're planted in situ - and left to their own devices.
Hope I helped - If you want me to look up a specific plant for you I might have some info in one of my books.
thanks so much poppysue you have been a big help!
im glad i didnt go to the garden center asking for situ!
wouldnt i have felt silly! LOL
that will help planting ALL these seeds, if i can plant a bunch outside!