You can post plant pictures to be ID'ed in the plant section if you like?
Swords are heavy root feeders, they often don't do well unless they get root tablets 1-2x/year.
Anubias tied down to Driftwood would work well too.
My tanks that you see under aquariums here all have ~2"; from my exp 2-2.5" fine gravel has worked well for the plants. But bare in mind if using Anubias or Java fern, they don't thrive when planted in gravel well, they rather wanna be attached to something (driftwood, rocks etc).
Yes def if you can stock the Cory's to 8-10 each that would do wonders for their schooling behavior (and I mean heck you have the room for them).
I perf like the Boeseman's (Pictures under my aquariums "Rainbows 55g") or Torquise Rainbows the best - But its your tank not mine, so you need to know what you like best
Tiger Barbs are the most active one's of all Barbs, also lil on the aggressive side there, I pers wouldn't wanna house these together with calm Tetra's.
If you want Gourami, get them, like I said your tank. Just from my pers exp with Rainbows when spawning they get territorial and that with the Gourami's IMO is a mix like the Tiger Barbs vs Tetra.
I try for more peaceful set up's in community tanks, if you have aggressive / territorial/ fin nippers among peaceful fish it may work for a while, but the permanent stress being chased around leads to other health issues (kinda like humans under permant stress) and that in the long run causes for short lives, issues within the stock of the tank yaddy ya - Nothing I pers like to deal with in my set ups - But like I said your tanks your call
In the combo of Cory and pleco you said you have (who else do you have for the bottom) I think i'd get 2 Clown's