I have 2 questions:

1.What are the available methods to resell the tokens after the ICO ends?
2.Can the user return the tokens after the ICO ends and get a refund? For example they buy X token for 1 BTC. Can the users can get back the 1 BTC after the ICO ends if they regret their decision?

[1.The user creates an account.2.The project automatically Create a wallet for each user.3.The project automatically send some bitcoins to the user's wallet.]

I need to create web wallets in my web project for each user. The scenario is as below:

1.The user creates an account.
2.The project automatically Create a wallet for each user.
3.The project automatically send some bitcoins to the user's wallet.

The questions are:
1.Is it an appropriate to use bitcoinjs to create the wallet for each user?
2.How can the user back up the bitcoin wallet?
3.how can the user take out the bitcoins from the wallet?

i want to create an ICO for my project and am wondering should i use crowdsale or dcorp. Anyone can provide any advice?