How should lists of questions be punctuated?

Solution 1:

I'd do something like

Dear xxx,

How are you doing with regard to

• sourcing the moose hair,
• reticulating the splines,
• extolling the virtues of silk underwear, and
• estimating the project completion time?

Basically, this just takes an ordinary list, punctuated as an ordinary list would be, and adds list bullets to aid readability. If you really wanted to, you could retain the colon after "with regard to", but I don't think it's necessary.

As with an ordinary list, if any of the list items contains a comma already, then replace the list-separator commas with semicolons:

How are you doing with regard to

• sourcing the moose hair, lamb tail, and armadillo feathers;
• reticulating the splines;
• extolling the virtues of silk underwear; and
• estimating the project completion time?

Solution 2:

A list is not really a sentence, so how you have it in your original quote would be fine. If you are looking to write out an entire sentence, you would place commas between each (being that the items are not clauses) and a question mark at the end:

How are you doing with regard to sourcing the moose hair, reticulating the splines, extolling the virtues of silk underwear, and estimating the project completion time?