Will there be a difficulty for mining the shares too? So if we get in on this early when the difficulty is low, we get more shares?
No, the purpose of WeCoin is to spread the coins equally between miners and investors.
There will be no difficulty so there is no instamine. Everybody is equal.
The longer you mine and the more hashpower you have, the more coins you get. It's a fair system. If you stop mining, your shares percentage will drop.