What is the maximum amount of investment from 1 address? For example, if there is no cap for 1 address then there will ne so called "whales" and manipulators who can whatever they what with the price of token on exchange, it will lead to the centralization
There is no maximum amount, I'm afraid. And setting a maximum amount wouldn't help either - the "whale" can quite easily create another address and invest from it. It's not possible to prevent this without introducing complicated (and potentially game-theoretically faulty) designs into the crowdsale model.
If you're worried that these "whales" could undermine the platform's economy - don't worry! First, the individual Subscriber's influence scales
logarithmically with their wealth, so a crowd of well-behaving subscribers will overwhelm a malicious subscriber with ease. Also, there will be a voting mechanism that will allow Subscribers to rescale the platform's prices if the DoBI/USD rate changes significantly. So the capabilities of "whales" in manipulating the platform are very limited.
I read your whitepaper and saw interesting point - self-promoting attack. Lets imagine the situation, for example, i am smart enough to create absolutely real fake accounts, and I will not only rate myself, but other amazing experts. If you think that people lazy enough do not do this, believe me some are not. So, how you will protect honest and smart experts, who deserve big rating from this totally the same smart guys, which are a bit trickier and have a lot of free time ?
It is practically impossible to completely block such an attack - a person crazy enough to spend troves of money on an attack would probably succeed. However, observe Bitcoin - its total cap is $66 billion, so a wealthy enough entity (some banks could probably do that with ease) could buyout all Bitcoin for $100 billion (considering the price will start to grow) and completely crash the system. But nobody does that, because crazy people rarely have enough money to blast everything to bits
The idea here is to create the system where such attack is not practically impossible, but economically infeasible. The potential profit from an attack must not be greater than its cost. So we introduce the aforementioned logarithmic scaling to cripple a wealthy malicious subscriber and force them to buy new accounts if they want to perform an attack. And so we try to design the system in such a way that buying Sybil accounts will cost more than the revenue from the possible reputation gain. To evade automatic detection an attacker will have to rate other experts both positively and negatively; but when you rate others positively, you increase their revenue and decrease yours! There is also a number of votes threshold and other counter-measures that will make the attacker spend more than they gain.