Bottling kombucha

Hi. I'm new here. I have my first batch of kombucha going. About two weeks in. I'm trying to figure out the best/easiest/cheapest way to bottle it for the double fermentation. Is it possible/okay to bottle it in store bought kombucha bottles (such as GT Dave/synergy with the white plastic cap)? I know when I purchased them there was a fair amount of carbonation in the bottles. Is it safe to reuse the bottles?

To double ferment, do I have to add fruit/fruit juice to the kombucha? Options?

Also the starter scoby I bought came with strawberry green tea bag. What should I use to start my next batch? Green tea, black tea, or a blend?

TIA.

I like the GTs bottles. Nice and thick. I haven't successfully gotten a good carb out of my kombucha yet. I think I'm waiting too late to bottle. But I've used sugar, fruit juice, and ginger trying to get it carbed.

You can make your tea out of any tea you like. Just be careful with teas with lots of herbs and additives. Plain black or green turns out great imo. But I also used lipton superfruit a few times and it's got a good taste.

I used the GT bottles at first but I switched to swing top beer bottles. You have a better seal with the swing tops so you get better carb.
I would second ferment with everything from fresh fruit, dried fruit (love my dehydrator) or fruit juice. I prefer fruity rather then herby KT. My favorite is grated ginger and lemon with a pinch of sugar.
As long as its real tea (Camellia sinensis) you can ferment it. Each KT will have a different color and base taste so experiment and find your favorite combo. Mine was 60 black/40 green.

I quit my gt bottles and went to straight bombers or i like 16 oz english type beer bottles.then use my capper. I love ginger bluberry. Ive use about any sugar i can to prime. Iv even gotten decent head from just raw sugar before! I usually do a week to carb depending on temps checking one after about 5 days.
I do half and half green tea black often but if your doing all green, you need to do some all black tea also,something about green tea that its not good to do only all the time. I like green tea but with kombucha for some reason it seemed that black tasted better, green is also suppose to give better carbonation.

I wouldn't re-use the GT Dave's bottles, they often have a pretty crappy seal to begin with. They've changed the caps in the last couple years and I'm not sure if it's helped or not, but the old ones used to leak almost all the time if you set them on their side in the fridge, and I mean serious liquid coming out, not just gas escaping.
Getting Kombucha to carbonate is spotty at best in my experience. I've heard others have gotten it down but even GT Dave's if you notice the same flavor will sometimes be carbonated, sometimes nothing at all (could also be due to their caps I guess). I've bottled one batch with the same amount of priming/flavoring fruit juice in each bottle (swing top bottles) and one of them exploded covering my entire closet with grape kombucha, while another in the batch was barely carbonated at all. If anyone has any clues to help me out on this I'd appreciate!

I thought swing top bottles allowed gas to escape therefore preventing explosions?

Unless you're thinking of some kind of swing top bottle I don't know about, definitely not. I'm talking about the "Grolsch style" with a metal hinge and rubber seal, and they definitely don't allow gas to escape or nothing in them would ever hold carbonation.

Yeah the swing tops do indeed allow gas to escape but only under high pressure. I over-carbed a lager and while I had insane carbonation some of the bottles had visibly seeped a bit.

I love the heavy GT'S bottles, but most LEAK. One company sells better replacement caps, but they are around $12/dozen. Virgil's root beer is hard to find, but great and comes in between EZ cap swing cap point bottles. nicer than Grolsch.