Welcome to the HOD Board, Heather!

I also work part-time and find HOD to be an incredible blessing for our family!

It flows beautifully, is full of awesome living books for all subject areas, is Christ-centered, and is totally open and go. One thing that makes it easy to use and implement for me is teaching it as it is planned, without substitutions and changes - plus, the things HOD has chosen are excellent anyway!

For these reasons, when you do PHFHG, I'd use the plans in the guide for spelling, R & S English, and science even though you used other resources this past year. The spelling is done via dictation- it is a busy homeschooling mom's dream!

It takes literally 5 minutes, moves incrementally through Levels 2-8 through all of the HOD guides, and done along with the copywork, Drawn into the Heart of Reading, writing, and R & S English plans in HOD - produces successful writers with better spelling skills, as well as strong editing skills. My oldest ds has completed Levels 2 through almost 8, started off as a so-so speller, and now rarely makes any errors. I credit the balance of HOD's LA skills through the years.
This leads me to R & S English - HOD suggests doing 2/3 of it or so orally or on a markerboard, reserving just one section to be written. This too does not take long but provides solid coverage and retention. The 5 oral review questions in the R & S English Teacher's Guide is the way to help dc retain English terms and procedures for clear writing better. R & S English is different from many grammar programs in that it teaches writing skills alongside grammar skills. The writing skills are important skills that help dc across all subject areas, such as writing clear paragraphs, outlines, reports, summaries, etc. They are not creative writing skills, which is where the creative writing poetry lessons in PHFHG come in.
The science ties to the history in PHFHG and uses living books. It is important to do, IMO, because it includes many important skills to be learned (and not just in the subject of science). It is an "I" box in PHFHG, which means it provides important training for doing science well 'independently.' This is key as the science in the following guide, CTC, is done independently and is more difficult. Each science unit includes the following skills...
Day 1: create a science notebook entry
Day 2: practice oral narration by retelling the science story
Day 3: write answers to five provided questions (including one Biblical application question) based on the science reading
Day 4: conduct an experiment related to the reading and log it in a science notebook or on a copy of the “Science Lab” form found in the Appendix
These skills are all built upon in CTC. If your dc are doing well with writing cursive, they need not do another year of it with a formal handwriting program. PHFHG notes in the plans times for dc to daily do small portions of copywork in cursive (i.e. within notebooking, etc.). If your dc need to practice their cursive formation more, then doing another year of your "A Reason for HW cursive" would be good. Keeping your Math-U-See and your Latin sounds like an awesome idea, as that is going well, and hopefully should not interfere with the beautiful balance of the PHFHG guide.

I would not try to do A Reason for Spelling, AIG, or Easy Grammar as it will be doubling up and will take longer and not cover the same skills so thoroughly covered in PHFHG's plans already. If you love AIG, one idea would be to do it only on Day 5, as PHFHG is a 4 day a week plan. However, this would only be if you love extra science - the plans in PHFHG are more than enough for science for PHFHG's target age range.
You asked about PHFHG in general - we have used it twice now different times with our two oldest sons and absolutely LOVED it! A few forever favorites from PHFHG for me have been "Grandpa's Box," "TIrzah," "Viking Quest," "Triumph for Flavius," "Fountain of Life," "Little Miriam of Galilee," "Little Riders," "William Shakespeare and the Globe," the "One Small Square" books and notebooking plans done with them for science, the staircase timeline created (we still have both of our sons' timelines up!

), the Psalms Bible Study and discussion, the introduction of Bible Quiet Time for our dc, the fun hands-on history projects, the creative writing lessons done with Robert Louis Stevenson's poetry (and our sons didn't love writing poetry at all before), the keeping of the Common Place Book, the drawing assignments from "Draw and Write," and the entire year with "Drawn into the Heart of Reading" and it's awesome book packs!
As far as ordering, you'd want...
1. Economy Pkg
2. Science Economy Pkg
3. Basic Pkg
4. Self-Study History Deluxe Pkg
5. Drawn into the Heart of Reading, Level 2/3, either with DITHOR Book Packs for each of your dc or with books of your own choice
6. Grammar - I'd guess R & S English 3 if they haven't done diagramming
7. Lead Me to the Rock (this is optional - this is a memory aid dc sing along with to better memorize the Psalms in the BIble Study of PHFHG)
Note: If you have to save money, and you have to drop something, I'd use your library for the DITHOR books of your own choice. Or, you could not get the Basic Package, which provides read-alouds for the history time period. However, it is set that has such great books in it, I'd really try to get it if possible!
HTH!
In Christ,
Julie