In a 1gal filtered and planted tank-I would do twice weekly 50% water changes and depending on the number and species of plants you may be able to maintain water quality with one weekly 50%
I have found that the stir and dip method the easiest to do on the 1gal tanks especially with rooted plants.
First-I unplug the filter and heater and then give the substrate a bit of a stir avoiding any plant roots to get the waste up in the water column and use a clean plastic cup and dip half the water out and replace with like temp dechlorinated water-plug the heater and filter back in and the water will clear after about an hour or two
The filter media needs a rinse/swish in old tank water a couple of times a month and when the water flow slows to get the gunk off to maintain good water flow.
Look forward to seeing pic....and yes, seeding the tank with established substrate from a healthy cycled tank is fine and will help jump start the nitrogen cycle.