Java fern does fine for me in tanks that run 70F in summer and 64-66 in winter. Since the water temp doesn't plummet at night, I think of it as warm water at those temps.
Lots of ways to add CO2, but remember, CO2 crashes pH and is toxic to animals, so be careful using it in a tank with animal life present. Search the web for yeast+homemade CO2 and you'll find a gazillion links. If you get serious about it, a regulator and tank can be used to inject bottled CO2. If you lose control, you'll buy a paintball refill tank and regulator from Craigslist like I did and have an 86 pound CO2 tank lol.
Ferts can be easy to add (Seachem brand aquarium ferts from PetSmart) or more difficult (powdered form from chemical suppliers), but it starts to get tricky balancing light/nutrients/carbon to keep algae at bay.
If you're interested shoot me a PM and we can discuss more.