Wow. Broad question. Where to start... ?

Ken wrote ...

now I need some good practical advice from people with good practical
experience.


Will you settle for just experience?

I'm willing to invest in a dual light strip... I'd like to avoid hooking up
a CO2 system
if I could, but will do so only if necessary and if it's inexpensive and
silent

That's a 15 US gallon tank, right? I'm sorry, I can't think in liters. If
you can get a twin strip (2 x 20 watt), that's all the light you're going to
need to get started with a lot of nice plants and, at that light level, CO2
is still optional. If you are interested in trying CO2, you'll have enough
light that your plants will benefit from it and, if you experiment with a
DIY setup, you won't have wasted a lot of cash if you decide you don't want
to keep it up. A single soda bottle system fed into a diffuser of the
intake tube to your filter is both inexpensive (things you probably already
have in the kitchen + standard airtubing) and absolutely-not-virtually
silent.

BTW, the barbs won't eat your plants but the pl*co may make an occasional
nuisance of himself scraping broadleaf plants. Mine eats anubias.

kush

"You can't have everything - where would you put it?"