Hiya Atlantic -
Well first of all it depends if the ebooks have been written by you and that you own them... If that is the case you can do what you like... If not then you need to check if you have PLR rights (Private Label Rights) as well as resell rights, give away rights etc... Otherwise you will be infringing on copyright....
I'm of the opinion you can do all of them - but if you do then make sure you change the title, description and covers for each one, as otherwise it will get noticed and the difference in prices will compromise your campaigns... With Clickbank (and other affiliate platforms) - if you are going to become a vendor then I would seriously consider developing a much broader package e.g. videos, audios, membership site etc.. As then you can charge more and in turn offer better commissions for attracting affiliates...
In addition I would definitely use them for list building - even if its a reduced excerpt version... Offering free/valuable incentives is a great way to build a list... and as such list building is hugely important as you can use that to promote other stuff through developing a trusted relationship and your dependency on traffic will diminish as your list grows...
I hope that helps!
Cheers,
Sid