Do I get plants right away, after a while, or after cycling? i thought i read having a planted tank will reduce cycling time- but now i can't find where i read that. How else would this change cycling?
When to add plants depends in large part on how you plant to cycle your aquarium. If you go with a fishless cycle, you'll want to wait on the plants until after you finish cycling since high levels ammonia plus lots of light tends to cause Green Water.
If you want to add plants sooner what you can do is a Silent Cycle. For this you would add plants right away (planting heavily) and let them get established and growing well for 2-3 weeks. After that you would add fish slowly keeping an eye on the Ammonia and Nitrites. If done correctly you should never see any Ammonia or Nitrite. The reason is that plants have lots of surface area for the beneficial bacteria to grow on and Ammonia/Nitrite/Nitrate is one of the nutrients that they consume.
If you aren't planting heavily and choose to do a traditional cycle with fish, then adding plants can help to reduce the cycling time since they will consume some of the Ammonia/Nitrite/Nitrate and will introduce some of the necessary beneficial bacteria. You'd need to keep an eye on the Ammonia and Nitrite, and be prepared to do large water changes to keep them in safe levels. Most people won't recommend a traditional cycle since there is a greater chance of accidently harming the fish involved, but the plants do decrease this risk some.
Will I need a heater? What about CO2 pump - i've read most plants need these but not java moss/ fern.
If you are keeping tropical fish and plants you'll want a heater. The need for CO2 injection is driven by the amount of light over the aquarium. Once you get more than about medium light CO2 injection becomes necessary as the ambient levels are no longer sufficient to keep up with the plant needs. All plants use carbon (which CO2 is a form) in varying degrees, even Java Moss and Java Fern.
Also, I've done some reading but what is your recomondation for a filter....substrate......air pump?
For this size aquarium, I'd probably go with a Aquaclear filter. They are high quality, inexpensive, and have lot of room for media.
If you're injecting CO2 then no airpump, but if you're not it's entirely up to you whether or not you use one.
With substrate you can get pretty much anything you want. Idealy it should be about 2-3mm in diameter and not have any sharp edges. Small gravel or Pool filter sand are a couple of easy options. You can also get into some of the plant specific substrates if you want.
As others have recommended, check out the Read This First Stick in the Planted Tank forum for links to lots of great information.
