I have a few questions:
1. At the beginning the company Ripple Labs created 100 Billion "tokens" and still owns ~70% of them and ~30% are (more or less) free floating. Is there more detailed information about how well the free floating ripple are distributed (something like X wallets hold more than 1$/10$/100$/1000$/10000$ worth of ripple)
2. Is it true that ripple labs can freeze or seize assets you have on their network?
3. If ripple tokens rise in value, how does this affect transaction cost?
4. What are ripples advantages against Stellar which is basically a copy of ripple, Counterparty, NXT and Bitshares, which are all competing in the payment processor space? (Acceptance by Banks?)
4. How is the ripple network secured, since POW and POS probably don't apply? (Not knowing much about the technicalities)
These are good questions and don't seem to have been answered so far...
1. You can see balances of every account on Ripple (XRP + IOUs) if you for example query a full ledger and look at the contents, I don't think there are pages like
http://bitcoinrichlist.com/ out there yet, they should not be too hard to set up though.
2. No, freezing is something the issuer of an asset can do (e.g. Bitstamp can freeze BTC or USD they have issued on Ripple) - if Ripple Labs issued assets (which they don't) they could freeze them of course, they can't freeze assets issued by someone else. XRP are not issued by anyone and thus cannot be frozen. Also you can set a (permanent!) flag in your account that prevents you from ever freezing any of your assets that you issue(d) with that account.
3. They get slightly more expensive. Currently one transaction costs about 0.12 XRP and 1 XRP costs about 1 cent, so while there is a cost, a Bitcoin transactions costs FAR more.
4. Stellar is a fork of Ripple which is currently struggling a bit to find their own way of doing things, Counterparty runs on top of Bitcoin which makes it inherently slow, NXT and Bitshares have an enthusiastic community but not yet a lot of use cases that I've seen (in comparison: you can get a Ripple-enabled credit card, you can send SEPA payments, Bitcoin transactions and US wires from within Ripple...). The biggest difference probably is that Ripple Labs has not only developers but also a business development team.
4. (again) - Consensus, the whitepaper was already linked:
https://ripple.com/consensus-whitepaper/