Hostesses?

A host refers to the person who pays. Someone who does a reading is a reader

I think the readings would be fine. It’s a nice way to honor them. Before they do the reading you can say something special as an introduction.

The host/ess pays, so that would be you. A reading is often done by the officiant. In many social circles, being on the guest list is a huge honor in itself without needing additional jobs. And not everyone wants to work. They are there to support your relationship and enjoy themselves. If you want, you can have a corsage made for them. But not necessary.

Please correct me if I am wrong but I think in some social circles a hostess at a wedding is a person of significance in your life you have guide people to your guest book, make people feel welcome at your reception, hand out programs, guide people to their seats etc. This is considered an honor but I have never actually seen one in action and for me I d feel bad asking guests to do anything other then have a good time. Aside from our bridal party & ceremony readers we have no other assigned roles, parents, siblings (and inlaws) ands god parents will all be given a flower as a thank you and nod to the special role they have each played in our lives. If a hostess is common in your circle then by all means go for it my family would have no idea what that is. Good luck!

In some circles the "hostess" is kind of the day of coordinator. It's a job that you would pay someone to do. I don't really see the honour there.

Why not have your friends be guests? That's an honour too! Another idea would be to acknowledge and thank them for their friendship in a speech or a toast.

Have them do a reading at the ceremony possibly

I think asking them to do a reading and getting them corsages would be a nice idea.