Great start!! Great that you research first. I just dove in and got a tank I saw at a LPS (local pet store).
The test kits do have and expiration date. After 6 months you probably won't need a test kit.
Now before you fill it put some plastic over the substrate. Thus less will float up.
I used metal flashing to keep substrates separate. I someone use plexiglass. Heated with a blow torch to bend it.
I would start with some cheap stem plants (wisteria) or floaters (Egeria densa) first to start the cycling. Some Pet Smart and Petco stores sell some. Also some tanks are prone to algae. Mine use to have BBA until I add 3hr siesta period with lights. After the cycling for plants check out plant finder
. I believe that light strip will give you medium light. You'll get more for you buck buying from someone on a forum like this 1 or APC
is a list of planted tank members in your area. Found it doing an advanced search on members. There is also aqua bid and online store
What ferts you will need will depend on the plants you get. My all in favoite fert is by select aquatics
Made and sold by a hobbiest thus cheap. Then I buy Brigtwell aquatics FlorinFE for extra iron off LNT.com, for they don't charge for shipping.
How did you find local used equipment store?