Stunt driver Ken Block in his ultimate playground.

[HooptieWagon]

5. Yes, you can disable the catch on the handbrake.

use a small clamp to prevent the catch from engaging and holding the brake on. Off-road vehicles had seperate L&R handbrakes, which might be used in autocross or drifting.
"Heel and toe" is a technique used in down-shifting, matching engine RPMs to the newer gear. Using a clutch, it prevents the rear wheels from locking up, without using a clutch it prevents gnashing the gears. This is not just for autocross or racing, I did it all the time in my MG and BMW using the clutch, and in my VW van w/o using the clutch (they only need clutch used when proceeding from a standing start, up and downshifts easily done by matching RPM and changing gears).
The Midget in video upthread probably isn't changing gears, looks like he's doing the course entirely in 2nd gear. Without gear changes, theres no heel and toe shifting. He probably has a heavy rear sway bar for lots of oversteer, and front alignment set up for a twitchy response. Probably using handbrakw on the U-turns, also.