Modding and compatibility issues

This may seem like a newbie question, but how do I create an item/block that also works with other mods (TE, MFR, Buildcraft, etc).

Case in point... I have custom crops that I want to be able to work with MFR's planter/harvester/fertilizer. I create the seeds, food and growth blocks, which work just fine planted with a hoe after I compile and place into the mods folder of a test modpack, but load the seeds into a planter/planter grid, and nothing happens. I have seen examples of other mods that work with MFR (Ender Lily seeds) and in their code they import "powercrystals.minefactoryreloaded.api.IFactoryPlantable". Does this api need to be included in the finished .jar? Will it conflict with MFR when i include the mod?

I also want to be able to have a block that accepts MJ or RF from a power source, but I know that may be beyond the scope of this thread.

Basically, how do I set up my environment so that I can test that my stuff is compatible with other mods.

Any information or links to tutorials would be helpful.