Java fern, anubias and anacharis are all easy plants with low light and low maintenance specifications. I'm not sure about adding them during a cycle tho. When you do add I would suggest taking an approach similar to adding fish. Add one or two and wait for a week or so before adding more. I have been slowly converting my non-planted tank to a fully planted tank and this approach has worked well for me. The java fernand anubias also do best tied to rocks or driftwood to keep the rhyzome in the water. Unlike other plants they do not absorb nutrients from the their roots so burying the rhizome can kill them. Anacharis can have part of the stem buried in the substrate to hold it down or can be allowed to free float.