New 18g tank: advice please

Hi all

I'm a newbie to the group, and a new, rapidly becoming obsessed, fish owner.
I acquired a new 24"x12"x15" tropical tank set up 8 days ago -- running a
Resun Magi-200 internal power filter. I filled the tank with tap water
treated with AquaMaster Chlorine Neutral, let the filter run for a day, the
added the recommended new tank dose of Cycle. The tank doesn't have live
plants, just plastic/silk plants plus some resin rocks, and a small gravel
substrate.

Four days later, I introduced 1 male and 2 female platys, and a further dose
of Cycle. The platys weren't real happy at first. Water tests next day
showed pH above 7.6 (not knowing better, I only got a narrow-spectrum test
kit), ammonia 1.0ppm, nitrates 0.3ppm. I haven't got test kits for GH/KH,
but the LFS tested and said the water is pretty hard. Our local water
supply has a high pH straight from the tap: not sure about hardness, but the
city was originally called Limestone! (Just a mild complaint -- test kits
here in Australia are quite expensive. And I wish I'd read up about
fishless cycling sooner).

Water yesterday -- pH: still 7.6, NH3/NH4: 0.51.0ppm, NO2: 0.1ppm. I did
a 25% water change and added 1/2 tsp pH-Down. pH afterward was 7.2.
Today's tests show pH back up, ammonia under 0.5ppm and nitrite 0.3ppm. The
platys are happy and eating well (tropical flake). I'll retest in 2 days.

I hope someone wouldn't mind answering a couple of questions or giving some
sage advice:

1. From what I've read, it seems like opening a big can of worms to try and
adjust the pH with pH-Down or other additives, especially before the tank
has cycled. (I understand that the pH will tend to acidify somewhat as the
cycle completes anyway, is that correct)? I figure I'd be better off
concentrating on fish species that will tolerate alkaline conditions, rather
than messing too much trying to get a lower pH.

2. The tank water smells like cat pee! (And no, the cat hasn't been peeing
in it, to forestall the obvious first question Is this normal? Any
thoughts? I wondered if this could be an effect of adding Cycle, or maybe
the tank decorations. Everything was washed well in plain tap water before
adding to the tank, and nothing had an obvious cat-pee smell.

3. Am I correct in thinking that the tank is still cycling, since ammonia
has dropped but nitrite risen slightly? Should I fork out more $$ for a
nitrate test kit? I should mention that the weather here has been quite
warm, up to 27 - 28 deg C during the day, if this has any influence on the
cycle. As it's too late to try fishless cycling, will 3 little platys be
sufficient to provide the biological load to keep the process going without
too much distress to them?

4. Has anyone had any experience with Geoliquid: is it worth using?

5. My thoughts on stocking the tank (focusing on small, hardy, peaceful,
alkaline-tolerant species):
a pair of dwarf blue or honey gourami
4 or 5 platys (including the 3 I've already got)
1 molly or 1 female betta
5 or 6 glolite or flame tetras, or else some WCM minnows
For the bottom: maybe a couple of bumblebee gobys, or else a peacock
gudgeon (if I can find one).

Does this sound reasonable? I'd appreciate advice on time span to
progressively introduce further fish, and whether it's best to introduce
them in any particular order?

Thanks in advance for your help. I've been reading as much as I can in this
and other groups, FAQs, aquaria web sites etc and am learning heaps,
especially about the fundamentals of the nitrogen cycle, and the importance
of good maintenance and regular partial water changes! I just hope I'm not
making too many huge blunders along the way.

Vicki PS