dunno about that co2 system looks pretty good with all the contact the co2 bubbles make with the water.
your co2 mixture sounds good although i never use baking soda. if your tank is big and depending on your lighting and how planted your tank is one bottle may not be enough.
Use aquarium silicone around the hole you made in the bottle top and let it dry for 24 hours and you should be good to go. Also use some kind of DIY co2 reactor so your co2 will get dissolved in your water.