Question about the Centrifuge chain

[LXHLeaner]

I have some question,please help me solve these,I would appreciate it !

First Question: Can you give me a public blockchain node?

Second Question: 
      What is the thransfer crowdloanclaim-claim_reward meaning?
      What is the thransfer parachainsystem-set_validation_data meaning ?

Third Question: If we have the api or others rpc to connect with the centrifuge chain?

Fourth Question: if you can provide others document about the centrifuge chain,in addition to "https://docs.centrifuge.io/build/cent-chain/#introduction", It can make me know more about the characteristics of this chain；

[mustermeiszer]

What you wanna archive here?