Was thinking of buying one for myself, thank you for those answers.
Can we keep all the ERC20 tokens and transact them with it.?
According to a quick google search, you can access ERC20 tokens in your Ethereum wallet through MyEtherWallet, or Geth, or Parity. I believe it uses the same Ethereum wallet that's natively supported on the ledger with the tokens, the first-party software just hasn't gotten support for ERC20 tokens yet but it looks like they're planning on adding it.
So to answer your question, yes, just not with the native app.