Hello, I'll try to answer your questions below however this is just how I see it! Others may have a different opinion.
1. The lower the turn motor then the faster the motor will turn I.e. Higher rpm for a given voltage. If you are just starting out then I would not start with a 4.5 mod motor rather id start with a stock affair 13.5 or 17.5 blinky. The 4.5 would be crazy fast for a newcomer.
2. In general the lower the turn the higher the current draw and so the faster the battery will drain. The higher turn (and lower boost etc) will drain the battery slower.
3. That figure is the ESC's highest continuous current supply ability. The pro ESC's are 120A and above whereas most of the stock ESC's are 40-60A. Get the highest you can afford as it will then cover you for future progress and hotter motors etc.
4. The speed passion reventon pro 1.1 or the Muchmore Fleta pro is a good esc for 4.5t. You can also consider the hobbywing v3.1 as well.
5. I don't know anything about the ESC's you quote. The most popular ESC's are speed passion and hobbywing it seems for touring car. Muchmore as well is popular in some places but not near me.
6. The motor brand doesn't really matter although I like to keep the same brand esc with the motor however it really doesn't matter! Some races require you to use a handout control motor which you use with your esc so don't worry about that.
I hope the above helps??
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Sanwa, Ielasi Tuned Novarossi Racing Engines, Tekin, Hobbywing, Muchmore.