Welcome aboard MB! 
Great to see such unadulterated exuberance. Hide your billfold, cut up your credit cards… you’re a perfect candidate for full blown flashaholism and will soon need dedicated flashlight cabinets. 
Biscotti (Bistro Mini) will work fine in the S2+, either with an 18350 or 18650. Your idea to use 8 7135 chips will give you a nice output on Turbo, also your idea to use the mode level 8 to prolong cell life for your half cell is right on target. You’ve researched it quite well.
Simon will gladly put a new updated driver in your purchase, just ask him and if there’s a charge for doing so he will let you know, most likely there won’t be. Tell him you’re a new BLF addict and rave like you’re doing here and he’ll know you’re one of us, he too is a flashaholic and your enthusiasm will appeal to him. 
Have fun! Modding is next… 