Thanks very much for the replies! I have the tank, and equipment is coming in from Amazon. A couple of thoughts I have ...
1. Apparently between my going to college, when I tore down my 10 gallon tank, and now, undergravel filters fell out of favor. I believe the professionals who are now recommending them correctly understood this bias against UGFs was due to manufacturer marketing. Like Gillette moving men away from 10¢ double edged razor blades to multi-blade cartridges costing several dollars each, amateur fish keepers were sucked in by this and bought all the negativity about UGFs thinking they were buying the next new wonderful thing. Now I've done a ton of reading on them in the last few days, some with very scientific analysis, and UGFs are coming back into vogue. I guess I'm glad I missed the bad days for UGFs.
My guess as to why I had such remarkable success with my tank back in the day is the UGF. I never had a test kit. And mine was an original, really old school one with skinny lift tubes (no airstone, just bubbles). I eventually got one with airstones and wider uplift tubes, and put a small HOB on it, as well. But without a test kit, I kept that tank going for years with 20% water changes maybe twice a month, and light vacuuming of the gravel. I didn't have any of the "knowledge" I've just gained, but that apparently helped. The KISS principle applies here, I guess. I will be using the
Penn Plax UGF and a
Marina S10 slim HOB filter.
2. I rewatched the KaveMan Aquatics video on quick cycling a tank for better understanding. I now know that the Prime should detoxify ammonia for the fish, and Stability is actually "bacteria in a bottle".
@bgarthe success and endorsement of the process makes me confident in putting 6-8 or so of those Harlequin Rasboras in the tank right away, continuing with the daily Prime and Stability dosing for a week.
3. I know that the tank will not be fully cycled at that point, but I may introduce another small species like neon or ember tetras at about 2 weeks, continuing with more Prime and Stability at that time.
4. I will introduce some corydoras at about week 4, maybe some more Prime and Stability then. I'll probably start water testing at that point, to determine when I need to start water changes. KaveMan says don't water change before that, count on the Prime to keep the fish healthy and let the bacteria grow.
5. Once they get established, I will introduce some easy and hardy live plants to the tank. I probably won't add more fish, as the purpose for this tank is to entertain grandkids and number of fish is not a big factor. Low bioload should help easy maintenance and make it more stable.
Any suggestions on this plan are welcome! I very rarely lost fish as a kid, probably because I had a good filter setup and tended not to muck with the tank much (laziness was lucky here).