Congrats on your daughter's engagement! Again, like everyone else, disneymooners has been a wonderful help to me - make sure your daughter visits the site too!
Cost will be very hard to gauge until after your daughter signs the contract with Disney (and Disney will give you no clues to costs until at least the time the contract is signed). I've found that the waiting is the most difficult part with Disney, but everything will fall in line! We invited about 50 guests to our wedding. We just sent in our adjusted head count and have 30 guests actually attending (keep in mind that even though many guests will tell you a year ahead that they will come - when it comes down to it, they realistically all cannot attend).
The first thing to decide is the wedding date, Disney will set aside a date and time one year in advance. If your daughter has her heart set on a specific day, call exactly 1 year ahead just to make sure you get it! As soon as she sets a date, she should also set up an officiant and a photographer. With Disney, you are not guaranteed the reception site until you sign the contract, but you wedding date and time are fairly well secured. We are using Jack Day as our officiant and Randy Chapman as a photographer (his rates are MUCH lower than Disney and other area photogtaphers). He also did our free engagement photos (came with our package) in January on our site visit and did a wonderful job!
We chose a Monday wedding beacuse it is close to the weekend, so that our guests who can arrive over the weekend and take as little time off work as possible. Also, this brought our minimum expenditure down to $7500. We also chose our wedding time at noon, so then our cocktail hour/reception will start prior to 2pm, keeping our overall food and beverage minimum at $75.
As far as reception menus, it will vary depending on their reception site. We chose Epcot's living seas lounge. The Epcot catering menu was reasonable and has menus of all price ranges. We chose a $60 plated meal, our cake is $8/person and we are doing a bar to be billed on consumption. We wanted the bar to be open during our entire reception and were not willing to pay $40/person for a package bar.......I figured out that on the package I would have to drink 8 beers to get to the $40 and I don't think it would be physically possible for me to do this! With bill on consumption, you tell your coordinator how many drinks per person to average into your budget (they average $5/drink). You will pay upfront for that amount and then if you have overpaid they will return the money to you after the wedding (if you underpaid, you get it taken from your $1000 deposit money). This way you only pay for what is actually consumed.
One of the other places we tried to save money is on floral. Flowers are really expensive and simple additions can add up really quickly. We chose just to have the traditional bouquets and boutanire's as well as a simple alter arrangement, which will be moved over to the living seas for our reception. At our reception we will have glass bowls with floating candles and flower pedals (about $10 each X 6 tables) as opposed to centerpieces which started around $30 a piece. They will try to suggest more floral, but considering that it is not coming home with us, there was not a point to order additional flowers. Both the wedding pavillion and our reception site are already beautiful without additional expensive add-ons!
Regarding your question about when to arrive. My parents are flying down two days before the wedding and leaving the day after. Mike and I are flying down 5 days before to make sure that we have more than one day to get the marriage license (just in case we run into problems/courthouse closing early etc). Also, that way we will physically be there when all of our guests arrive. Disney will also offer to set aside a time for a wedding rehearsal. We set ours up for 4pm the day before the wedding.
Overall our wedding is going to cost around $11,000, photography is around $2500, the officiant is $175 and dress steaming is $60.