I have one question about referrals that didn't add their withdrawal address - so if a user signed up via a ref link and didn't add a BTC address, I guess we don't see it on the referral list? I have a friend who was interested in this, but when he tried to add his bc1 (native segwit) address, it was unfortunately not supported - isn't it time for this service to make it possible?
You can still send to native segwit bech32 addresses if you request slow or instant withdrawal. It is only not supported for auto-withdraw because they don't want to take the site offline to implement it.
Yes, you can. Bech32 addresses can be entered on the withdraw page but you can't set the default withdrawal address on the profile page. Adding that requires a major database reorganisation that would require a lot of downtime.