hokicake

So I just got a aero frame road bike in the smallest size avail and the top tube still touching my privates but at least I can stand over it but I would like a like some clearance so I'm gonna put on 650b tires to drop the frame a little bit. I just got some mavic wheels in the mail and got some 27.5 x 1.5 tires so I'm hoping it'll fit cause I'm just playing it by ear. The main concern I'm having is the brakes cause the ones I have on there now are very short arm ones so I'm wondering what size do I need to reach if I can even do that cause these wheels I got just say disk brake wheels and I donno if I can use pads on those rims but they say they are s6000 double wall aluminum so shouldn't that be strong enough? I might be able to put on disk brakes and I already ordered all the disk brake hardware for it in case I wanna do that but the thing is the bike doesn't have the built in holes to mount the stuff so I ordered disk brake adapters that clamp onto the frame and spindle thingy to provide the two holes but I wasn't sure about that cause I was reading where people have said it might bend the frame cause the frame isn't ment to support that force or something so I was thinking should I just put on long arm brakes to do a rim brake even if the rim doesn't specifically say it can do that cause it's not like I'm going to be doing some serious speed and hard stops anyways and I would think if braking is done on both wheels it's not like one side is getting all the force anyways and I feel same thing can be said about the disk brake adapters too. So what should I do? I'm so confused.