Mine only helps if your friend chooses to hire servers (since not all caterers and venues provide service). I wish I'd hired two more servers than I did (we hired two but could've used four; we tipped our servers handsomely at the end of the night, in addition to what we agreed to pay them, as they worked super-hard for us). Also, if your friend is in the US/getting married in the US and chooses to hire servers to make sure they are currently Serv-Safe certified (not hard to do as they'd receive both a certificate and a card to carry around confirming their certification; I knew to advertise for servers at the local professional culinary school that I also attended). Serv-Safe certification means they know proper and safe food handling and sanitation procedures.
Pod the advice to have a spreadsheet set up. I set up a spreadsheet and wrote formulas to calculate and compare costs. The spreadsheet also made it really easy to do the seating chart since I could easily move the cell contents around from column to column (each column was one table). Also used it for guest names and addresses then it was easy to set up a mail-merge for the labels. Really, except for the floor plan, I used my spreadsheet for everything, I think.
Finally, a to-scale floor plan of the venue would be great. I did one for mine and had on it the table numbers, which then corresponded with which cake went where (my multiple wedding cakes doubled as centerpieces), and what additional tables and what went on them went where (such as the guest book table, the appetizer table, food tables, etc.). Since it was to-scale, then I could accurately determine spacing for the tables (it was how I figured out that even if we could afford it, there was no way we'd be able to have a band as there was no room in the hall size we rented).
I love the idea of a scrapbook. I didn't consider that when planning. However, while in the midst of decluttering and sorting through paperwork, I've come across wedding-planning items here and there that I set aside to keep, and I think a scrapbook of those items would be great.
So not to seem like pushing her in any direction, maybe suggest she take pictures, get samples (like fabric colors, dresses, cake styles, etc.) of all the elements she's considering so she could lay them out together and see what of her ideas works/doesn't work?
My wedding occurred during winter in Northern CA, and my family all came from Southern CA so I made sure to mention on our wedding website to dress warmly. Your friend might want to keep temperatures in mind if her wedding is outdoors. DH and I went to a family wedding a few years ago where the reception was outdoors. It got cold and breezy pretty fast as the venue was near the ocean; several guests either sat there clearly cold or had gone to their vehicles midway through the reception to grab a jacket. It was clear even the HC didn't consider that part by having an evening reception as even the bridesmaids were seen wearing the jackets of the groomsmen as no one had planned for it to get cold outside (it was summer but we were a mile or so from the ocean).