Shalom and welcome aboard, Elie!
Chacham Yitzchak Yosef has updated all the Moadim volumes over the past decade, and they are sold separately. Ultimately, they only replace one volume of the old set. In addition, he updated the first volume of Hilchot Shabbat before that and split it into more volumes. Those are sometimes sold separately and sometimes as a set. You should definitely get those newer volumes, as they incorporate updated pesakim from Chazon Ovadia plus many many more sources and discussions including more contemporary sefarim quoting Rav Shlomo Zalman Auerbach and Rav Elyashiv.
They can all be purchased from local Jewish bookstores in the US. Take a look at ZBermanBooks.com, JudaicaPlaza.com, Eichlers.com, ShopEichlers.com, MekorJudaica.com, Nehora.com, SeforimCenter.com, JudaicaSpot.com, SeforimSets.com, Biegeleisen, GreenfeldJudaica.com, SephardicWarehouse.com, MySefer.com, etc.
You can probably get a good deal plus free shipping from Judaica Plaza or Shop Eichlers, but ZBerman often has the best or at least a competitive price. Contact them if you need anything, and they'll get it for you if they can. No need to purchase and ship something from Israel when you can have it here in a couple days from a local store.
He also redid the volume on Sheviit seven years ago, but I haven't checked to see which one comes in the current set.
Many of the new volumes are available for free on HebrewBooks.org (free) and, of course, and Otzar Hachochmah (paid). Bar Ilan's Responsa.co.il does not have all the new volumes.