Wishes can be added to a basket and paid for in one go. Memberships, Bills, paid requests and shop orders are bought one at a time, because each sets up its own arrangement.
Wishes go into a basket, and you pay for them together in one checkout.
What cannot go in a basket
Memberships, Bills, paid requests and shop orders are bought one at a time. Each of those sets up something specific — a recurring arrangement, an agreement with the creator, or an order to be posted — so each has its own checkout.
Buying from more than one creator
You can. Each creator is paid for their own items — see who is the seller.
Without an account
A basket of wishes can be paid for without signing up. Some purchases do need an account, and there is a reason for each.
The total
The number at checkout is the number you are charged. Why it differs from the listed price is explained in why is the total more than the price.