It needs to be a mixture of other sites and ebay, it looks more natural that way.
all anti detect softwares are similar except for thunderbird, if you can get your hands on thunderbird, you should use it. Otherwise, multilogin, gologin all provide better protection than not using anything.
there is no exact time really, the point is not to use it immediately after its creation, but to accumulate history and cookies. It would be suspicious if someone use a brand new browser to open an ebay account. I used to go by 2-3 months warm up, but now due to the sheer number of accounts, we have limited labor capabilities, so we kinda shorten the warm up period a little to make it easier for us to manage.