Scales Harmonization and Figured Bass - from Dupré's Organ Improv Course

[kalospiano]

Hi all, I recently bought this book as I wanted to obtain more familiarity with classical improvisation and I was told that this was an excellent manual also for pianists. Hope some of you might be familiar with it and give me a little help with the first three exercises, as I'm already stuck at the very start.

 - The exercises are outlined but there's not even an example given. The first exercise is the four parts harmonization of the major scale. The scale notes are on the top voice, and the other voices are given only for the first degree: the third in the alto, the fifth in the tenor and again the tonic in the bass. I suppose I should always keep this format for each of the degrees, or should I switch it up?

 - The second exercise has some figured bass: I'm familiar with what 6, 6/4, 5/3 and other indications mean, but what does it mean when there is just a 5, or just a 3? I've found a web page suggesting to to play 8/5/3 whenever the figured bass is 5/3 or just 5 or just 3 or there's no indication at all... but if they are really the same thing, what sense would it make for the figured bass to change from 5 to 3 for two adjacent scale degrees in the exercise?

 - The third exercise starts with "the pedal must always proceed in the opposite direction of that of the given scale (contrary motion)", but then adds "harmonize the 12 major scales (...) placing the scale in the pedal"... what gives? Isn't it the exact opposite of what stated initially? Also the ending says "the soprano must procede in the opposite direction of the scale"... I'm confused. Could it just be a misprint or am I missing something? I guess possibly the first sentence was still referring to exercise number 2...

Sorry about the long text, it's complicated to explain this stuff in text but I hope some of you might help me. Thanks in advance!