the weather in the end of September can be hit or miss. However, the annoying overcast clouds we experience for several weeks in the winter months shouldn't be present then. So at least if there's a high pressure area, the weather should be good. You might even see some beautiful autumn tree colours like in this picture (from my website), but you might be a bit early for that.
I've got a very detailed spotting guide on my website (in english), explaining more than a dozen positions.
For the 9 most popular positions (numbers 1-9 in my guide) you won't need a ladder. All positions except nr. 6 provide an elevated view which lets you see over the fence, and at nr. 6 there are about 10 holes built into the fence especially for cameras. They can fill up on nice weekends (and Wednesday afternoons, when kids don't have school), so in those cases you need to be early.
These positions let you see all movements. I especially recommend position 6, which is very impressive for widebody takeoffs off Rwy 16 between 12 and 2PM. Of the smaller "special" spots I outline, M4
is the only one that needs a ladder, but this one is only suitable for late summer evenings anyway. So to sum it up, you're fine without a ladder.
Here's a photo from Spot 6, of course it was only that full because of the A380's first flight.
There is public transport available around the airport, originating hourly from the terminal area (Bus Nr. 510, further explanations in my guide), however you would need to walk about 15-20 minutes per way to the spots after getting off the bus. If that's too much, you're better off renting a car. You can also rent a bicycle at the airport, which is a great way of getting around ZRH
since there are bike paths all around the fence.
If you have any further questions, drop me a line via my website, as I'm not on here too often.
Tis (leaving for holidays in your country tomorrow