2. Straight arms and bent wrists - puts A LOT of weight on bars and causes wrist pain. Having upper-body weight resting on bars makes them difficult to turn. This is the slow-response you're noticing. It's not the bike, but from your arms fighting each other in opposite directions.
You'll want to position your arms and wrist exactly same way as with upright seating position:
With bent-elbows and wrists in-line with forearm. This removes upper-body weight from bars and allows you to push/pull on bars easily for fast maneuvering.
With elbows bent, forearms are parallel with ground and wrists are straight, exactly same as with upright position. Without any weight on bars, you're not fighting upper-body weight to turn bike. As far as front-tyre's contact-patch is concerned, it can't tell if you're sitting fully-upright or fully bent over. Personally, I prefer my bars at same height as seat. This lowers CoG of bike+rider package and makes for faster transitions from full-upright to full-lean (head & upper-body moves through shorter arc for same lean-angles). Not to mention more aero for faster top-speed on straights.
I chopped fairings to lower bars 6" compared to stock. Then raised them 2" when selling bike.
3. Muscular strength - Of course, this riding position requires strong back-muscles to hold upper-body without putting weight on hands. Even though I'm not racing velodrome any more, I still take 1-month in winter to build up strength in arms, back & legs. We all lose strength over course of year, especially with age. I've found roman-chair back-lift exercise shown below to be most effective. I start with barely being able to do 10-reps in beginning to doing 20 easily while holding 25-lb weight to my chest (some people put weight on back of shoulders). Really helps with moto-racing as I'm no longer fatigued and tired by end of day. Even did 4 trackdays in row once with 2 of them going out in both B and A groups (that's 5-hrs/day)!
