Who decides that a new user get 145 delegated SP? Which mechanism is working towards that? Is it random or have some rules?
145 SP would give 2-3 cents I guess.
It has to do with the minimum account fee at the time the account was created, and when the STEEM price was lower the minimum account fee was a lot higher (in STEEM, but comparable in fiat value)
1. How does SP affect the value of the vote? - accurate calculations showing how SP affects our upvote at 100% VP.
It is linear. The exact calculations are complicated but to keep it simple twice as much SP = twice as much reward value (assuming 100% vote power). There is also a hidden vote power that kicks in if you vote too much (more than 10 full-power votes per day) and reduces your votes proportionately (if you full-power vote 20 times, each will be half as strong).
So if we want to optimize our curation rewards, we should vote 10 times a day, each 2.4 hours, right?
That would be one way. But the automatic adjustment means if you vote 20 times per day your vote power will drop to 50% and the aggregate will be the same. However, you will be able to split your votes 20 ways instead of 10, which could be better (if anything lower risk of choosing poorly). Another option would be to vote with 50% weight 20 times. There are many other possibilities. What matters is the total amount of voting per day (to be precise over 5 days). Can't exceed 10 full power votes per day, or everything gets scaled down to the same total.