eBay selling?

I have a ton of Kobe Bryant, Tim Duncan, Ray Allen, Allen Iverson, T-Mac, etc., rookie cards. The Kobe's seem to be selling for $500+ so I'm thinking about getting some graded and then doing eBay. Best one I have is Kobe Topps Chrome and then the Topps version of it as well.

For those who are in it (I haven't paid attention to cards for 25 years now)...

1. For cards worth $100-$250ish think it's worth it to pay the $20 PSA fee? Does seem like it earns a premium if you get an 8 or 9.

2. I've already submitted the only 3 I had graded (BGS at 8.5 each), but for cards not in cases any recommendations on best card holder to ship them in to PSA?

3. For selling on eBay, I have dozens of cards like Steve Nash, Chauncey Billups, Jason Kidd level players where I won't get them graded but will see if I can get anything for them. Think it's better to sell individually or try to package them together (i.e. 10 Chauncey Billups Rookie Cards: Fleer, Topps.....)? My 15 y/o son will post and manage (for a cut :)) so not too worried about efficiency more about what will sell the best.

4. Auction work on lower value cards or is that best for the $500+ type cards? If I'm selling a $20-$50 card just do Buy It Now?

Any tips welcome! A relative told me there's been a surge on basketball cards lately so I had my parents ship me my old collection and was pleasantly surprised to see they have actually gained in value! Might have a few grand sitting in there we'll see.