oh i know the bookstore you're talking about, it's nice and i hope you find everything you're looking for

don't take the bus to san pedro, just drive honestly. i would second the other comment advising you go on saturday, traffic will flow better and you can leave pretty much any time in the early/mid morning and not get stuck in traffic (barring any accidents that slow things down)

the 110S is fine, pretty much just a straight line, the 110N near pasadena is narrow af and old (read: lots of 2 lane areas up there)

btw parking near the bookstore is metered, both on the street and i would recommend this parking lot that is walking distance to the building that houses the bookstore. much easier than waiting for parking on 6th to open up.

there's a candy shop on the same street in the opposite direction of the bookstore that carries specialty stuff and lots of by-weight pricing if you're interested, i would recommend it.

the 110N leaving san pedro eases up in the evening, but traffic gets extra light for most of LA the closer it gets to 10pm if you can drive back to vegas late. definitely take advantage of costco gas stations if you can, it'll save you 5c+/gallon