If you are going to be dosing flourish excel which is a just a source of carbon for the plants, then you need to dose micro nutritients and macro nutritients, otherwise your plants will suffer and you'll get algae. They need all these to grow+ light which you already have. Also, flourish excel should be dosed daily as it has just a 24 hr life cycle and micro(also called trace elements) and macro(nitrate, phosphate, potassium, etc....)ferts on alternate days(never together as some can react with each other). Be careful with flourish excel because in high doses it's dangerous to sensitive fish and inverts. Start with the recommended dose on the bottle, but spread daily.
Root tabs contain certain type of nutritients, depending on the brand. Most contain just micro nutritients, so it's just a partial supplement. They are good for heavy root feeders like echinodorus species but most plants will take that from the water column so liquid micro and macro ferts(or a comprehensive fert that contains both) is fine too.
When dosing carbon, you are technically converting the tank to "high tech" so you'd need weekly 50% water changes to reset the tank in case one goes nuts with dosages and it's important when dosing excel too as it produces bioproducts.
Personally, with just a couple of plants in the tank, I'd just either leave it to the fish waste to provide all nutritients, but still use root tabs locally just near the plants. Once you properly plant the tank and possibly research on how it all works, you can start a full program.
As for the plants, always remove all damaged leaves, leaves with brown spots,etc...they won't magically recover so remove the yellow leaf too. That runner may start to melt too.