If you're over 50 then look at one of the retirement visa options. There are a variety to suit different situations. If you're under 50 then look at the Thai Privilege visa
Thai immigration won't care unless they're looking for a reason to deny entry. Your airline on the other hand might not let you board your flight without an onward flight from Thailand, it's them you need to ask
I wouldn't bother getting a visa for your daughter, she can't be on a non-o once she hits 20 anyway. There are a couple of options open to her after she arrives but the first thing she's going to need is a Thai ID card. This page is worth a read for her situation
Having a business is one thing and working in that business another thing. For the latter the business will need to sponsor you for a non-b visa and work permit, that requires 2m baht registered capital and employing 4 thais.