I think you don't have the basic idea about bitcoin as to invest in btc the basic idea about it is the first and foremost thing. I would strongly recommend you to study about it very well so that you will be clear about all the confusions you have right now about btc.
Actually IP means Intellectual property that means a right of a human on his own innovations based on this Kakushin is based on their IP and also its cheap so people trust this more than others.
I think there is no difference between these websites but in case of this myetherwallet is more trustable but many people are switching to MYCrypto almost many developers have been switch based on their benefits.
Considering them as a start up wouldn't be right because they have been in operation for a while. The correct term would be to consider them in an infant stage. They are also termed as crowdfunding project by the users.
Basically I search in web and I learned that it’s a projects based on this it work for ad which is work for one time when it play once then it will be removed so there is nothing to worried about this matter.