JScott613's comment about AVOID OILS for KT brewing is correct. There are SO SO many varieties of teas. When I first started KT brewing and wanted to branch out to different varieties I asked for help from a few of the sites that sell Kombucha mothers. I came across Nick's Natural Nook (I always find them on eBay & I saw them on etsy) & if you message them they will let you know what teas they carry are appropriate for KT. They even have variety packs that you can custom build, so you can have a minimal investment, try the tea with your scoby & then know whether that one works for the taste you are seeking or enjoy. Their teas are organic & my first variety pack included: almond blossom oolong, honeybush, assam, and green chai. They have over 25 varieties, though I don't know how many are appropriate for KT. I enjoy all 4 that I purchased & I like to use assam as a base and blend with any of the other three, or as a stand alone I think I like the almond blossom oolong the best....but that is just me.
In regard to carbonation, IMHO, (I use mason jars), I will do my primary ferment in a loosely capped jar until desired level of sweetness, if I want a secondary ferment I will then proceed with that but typically no more than 3 days with the lid tightly capped, the jar wrapped in a towel & I "burb" the jar on a daily basis. I check for appropriate level of sweetness before I bottle & if I have to I will back-sweeten and then bottle in a grolsch style container and refrigerate. When I pour a glass on ice, I get loads of fizz. I am very, very cautious when I ferment with a tightly capped lid, and even take one extra level of security and place my brew container in a cardboard box or styrofoam cooler--just depends on how many different KT's I have going. I watch for great prices on french lemonade or other items packaged in flip-tops and will use them for my KT, kefir water, ginger beer, fruit cordials(non-alcoholic & alcoholic) and wine(that will be consumed shortly rather than left to age). If I need the flip-tops in bulk I purchase from my LHBS or check prices at online container sites. I do have to say that all this home brewing/fermentation is quite addictive & it seems like the only thing I honestly don't make at home is beer(though that is on my list). I do different yogurts(CSY, greek), sourdough and am getting ready to start vinegar! Cross-contamination of cultures is my biggest fear and I always make sure to use well ventilated spaces and keep any different cultures being used at least 8 feet apart----in the past year I have not yet killed my cultures. Anyway, I do enjoy the forum!