I'm trying to understand my cooling system, and maybe I'm the one that's broken

[sapote]

Everything you described sounds perfectly normal.

"But somehow, in certain conditions (going downhill, going through colder area), the temperature keeps dropping up until the needle hits roughly around the first dot."
The first dot is 73C which is too low.

[Cubieman]

You can definitely reuse the clamps on the T.B side, also a pair of needle nose pliers can be used to re-install them. No need to buy new intake boots unless yours are damaged.

The proper pair of pliers with the little tiny prongs can usually be had for $15 on Amazon, makes things easier.

Its really not that bad of a job.