You should be able to either find that hood in the store or check online, most likely the best place you can find one.
And yes, plants can grow in gravel as well as sand or dirt or small river rocks.
Good plants for low lights and beginners are: Java Fern, Java moss, Anubias, Anacharis, Vallisneria, Rotala, Ludwigia, Hornwort, cabomda, water sprite, water wisteria and common Cryptocorynes.
Java Fern and Anubias both have things called Rhizomes, basically it's the part that roots come out of on bottom and leaves shoot from on top, so it's sort of like a crown. But that thing cannot be buried in anything, the roots can be buried just fine but not the Rhizome. Java Fern and Anubias can also be attached to decorations, rocks and driftwood and they will grow! You just have to tie it lightly with thread or fishing string and in about a month or so, voila, you have a plant on an ornament/rock/driftwood.
Some of those that are more bushy would be the stem plants; Cabomda and Hornwort although Water Sprite and Water wisteria are both great choices too! You can also float Water Sprite, Hornwort and Anacharis.
So those would be good easy plants, they help with water quality too. Also know that sometimes (especially crypts) will melt or lose leaves when first introduced to the aquarium, this is completely normal and will grow back in a week or two. It's basically just acclimating to your water. And no, plants don't need a QT time unless you feel it should be, then you can leave them in regular Tap water with a light or on a window sill to get sun. But I throw mine in right away after trimming the roots a bit and plucking off dead leaves.
When you see leaves turn brown then yes that is a dead leaf and just pluck it off so the plant can grow a new leaf
Also it might benefit your plants to get a liquid fert like SeaChem's Flourish Comprehensive. It's a little pricey but it's so worth it. I use 1 drop per gallon twice a week and my plants have never looked better! So I highly suggest it and it's pretty easy to use